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KRISHNA MURTHY IIT ACADEMY.

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Presentation on theme: "KRISHNA MURTHY IIT ACADEMY."— Presentation transcript:

1 KRISHNA MURTHY IIT ACADEMY

2 VIDEO LESSONS

3 FUNCTIONS

4 Let X and Y be two nonempty sets of real numbers
Let X and Y be two nonempty sets of real numbers. A function from X into Y is a rule or a correspondence that associates each element of X with a unique element of Y. The set X is called the domain of the function. For each element x in X, the corresponding element y in Y is called the image of x. The set of all images of the elements of the domain is called the range of the function.

5 f x y x y x X Y RANGE DOMAIN

6 Determine which of the following relations represent functions.
Not a function. Function. Function.

7 Not a function. (2,1) and (2,-9) both work.

8 Find the domain of the following functions:
B)

9 Square root is real only for nonnegative numbers.
C) Square root is real only for nonnegative numbers.

10 Theorem Vertical Line Test
A set of points in the xy - plane is the graph of a function if and only if a vertical line intersects the graph in at most one point.

11 y x Not a function.

12 y x Function.

13 Domain of a function represents the horizontal spread of its graph & the range the vertical spread.
4 (2, 3) (10, 0) (4, 0) (1, 0) x (0, -3) -4

14 One-to-One Function On-to Function Inverse Function

15 A function f is said to be one-to-one or injective, if for each x in the domain of f there is exactly one y in the range and no y in the range is the image of more than one x in the domain. A function is not one-to-one if two different elements in the domain correspond to the same element in the range.

16 x1 y1 x1 y1 x2 y2 x2 x3 y3 x3 y3 One-to-one & on-to function
Domain Co domain x1 x2 x3 y1 y3 Domain Co domain One-to-one & on-to function NOT One-to-one but on to function One-one but not on to function Domain Co domain

17 ON-TO or Surjective function
A function f is said to be on to if every element of the co-domain is the image of some element of the domain. That is for all y in co-domain, there exist x in domain such that y = f(x). ON-TO ness depends on co-domain

18 BIJECTIVE FUNCTION A function is said to be objective
if it is both one-one and on-to x1 x2 x3 y1 y2 y3 Domain Co domain

19 Use the graph to determine whether the function
is one-to-one. Horizontal line Cuts the graph in more than one point. Not one-to-one.

20 Use the graph to determine whether the function is one-to-one.

21 Let f denote a one-to-one function y = f(x)
Let f denote a one-to-one function y = f(x). The inverse of f, denoted by f -1 , is a function such that f -1(f( x )) = x for every x in the domain of f and f(f -1(x))=x for every x in the domain of f -1. .

22 Domain of f Range of f

23 Theorem The graph of a function f and the graph of its inverse are symmetric with respect to the line y = x.

24 y = x (0, 2) (2, 0)

25 The function is one-to-one.
Find the inverse of The function is one-to-one. Interchange variables. Solve for y.

26 Check.

27

28

29 Even and Odd Functions Even functions are functions for which the left half of the plane looks like the mirror image of the right half of the plane. Odd functions are functions where the left half of the plane looks like the mirror image of the right half of the plane, only upside-down. Mathematically, we say that a function f(x) is even if f(x) = f(-x) and is odd if f(-x) = -f(x).

30 Some Examples even functions odd functions                                                                                                                                                                                                                    f(x) = |x| f(x) = 1/x

31 f(x) = x2 ,Even f(x) = x3 , Odd

32 y = cosx, Even y = sinx, Odd

33 Is there a function which is both even as well as odd?

34 Yes there is Only one function which is both even as well as odd

35 The function is y = f(x) = 0
Let y = f(x) be one such function Then, f(-x) = f(x) and f(-x) = -f(x) So, f(x) = -f(x) f(x) = 0

36 PERIODIC FUNCTIONS

37 A function f is periodic if there exists some number p>0 such that
Periodic functions are functions that repeat over and over, or cycle on a specific period. This is expressed mathematically that A function f is periodic if there exists some number p>0 such that f(x) = f(x+p) for all possible values of x The least possible value of p is called the fundamental period of the function.

38 f(x) = sinx, is a periodic func with fundamental period 2π
f(x) = cosx, is also a periodic func with fundamental period 2π

39 are periodic functions with fundamental period π
y = tanx & y = cotx are periodic functions with fundamental period π Graph of y = tanx

40 A property of some periodic functions that cycle within some definite range is that they have an amplitude in addition to a period. The amplitude of a periodic function is the distance between the highest point and the lowest point, divided by two. For example, sin(x) and cos(x) have amplitudes of 1.

41 A.f(x) + B.g(x),where A and B are real numbers is
COMBINATIONS OF PERIODIC FUNCTIONS There are no hard and rigid rules for finding the periods of functions which are the combinations of periodic functions but the following technique may work in many cases. If the period of f(x) is (a/b)π and that of g(x) is (c/d)π ,then the period of A.f(x) + B.g(x),where A and B are real numbers is (LCM of a,c)/(HCF of b,d) times π

42 For example, find the period of
y = sin7x + tan(5/3)x. Period of sin7x is 2π/7 and that of tan(5/3)x is 3π/5. Hence the period of the given function is (LCM of 2,3)/(HCF of 7,5) times π that is 6 π

43 If the period of f(x) is p then that of a.f(x) + b is
also p and that of f(ax+b) is p/|a| For e.g, period of sin(4-3x) is 2π/3

44 If f(x) is periodic and g(x) is non periodic then
f{g(x)} is not periodic except when g(x) is linear. For e.g, y = sin(4-3x2) is not periodic

45 A constant function is periodic but has no fundamental period.
y = x – [x] is a periodic function whose fundamental period is 1

46 Increasing & Decreasing Functions
BEHAVIOR OF FUNCTIONS By behavior of a function, we mean, its Increasing & Decreasing nature Increasing & Decreasing Functions

47 x1 < x2 implies f(x1) ≤ f(x2)
A function f(x) is said to be increasing in an interval, if for any x1, x2 belonging to this interval, x1 < x2 implies f(x1) ≤ f(x2) OR x1 >x2 implies f(x1) ≥ f(x2) That is, if x increases then f(x) should increase and if x decreases then f(x) should decrease. The function is said to be strictly increasing if x1 < x2 implies f(x1) < f(x2) x1 >x2 implies f(x1) > f(x2)

48

49 The function y = 3x is strictly increasing

50 x1 < x2 implies f(x1) ≥ f(x2)
A function f(x) is said to be DECREASING in an interval, if for any x1, x2 belonging to this interval, x1 < x2 implies f(x1) ≥ f(x2) OR x1 > x2 implies f(x1) ≤ f(x2) That is, if x increases then f(x) should decrease and if x decreases then f(x) should increase. The function is said to be strictly decreasing if x1 < x2 implies f(x1) > f(x2) x1 >x2 implies f(x1) < f(x2)

51 The function y = tanx is strictly increasing .
The function y = -[x] is decreasing but not strictly decreasing DRAW THE GRAPH and verify.

52 MONOTONIC FUNCTION A function is said to be MONOTONIC in an interval if it either increases or decrease in that interval but does not change its behavior.

53 increasing in its domain
The function y = tanx is monotonically increasing in its domain

54 The graph of y = cos x This function is NOT MONOTONIC

55 Library of Functions, Piecewise-Defined Functions

56 f(x)=mx+b A linear function is a function of the form
The graph of a linear function is a line with a slope m and y-intercept b. (0,b)

57 A constant function is a function of the form
f(x)=b y b x

58 Identity function is a function of a form:
f(x)=x (1,1) (0,0)

59 The square function

60 Cube Function

61 Square Root Function

62 Reciprocal Function

63 Absolute Value Function
f(x) = |x|

64 When functions are defined by more than one equation, they are called piece-wise defined functions.

65 For the following function
a) Find f(-1), f(1), f(3). b) Find the domain. c)Sketch the graph.

66 a) f(-1) = = 2 f(1) = 3 f(3) = = 0 b)

67 c)

68 Polynomial Functions and Models

69 A polynomial function is a function of the form

70 Determine which of the following are polynomials
Determine which of the following are polynomials. For those that are, state the degree. (a) f ( x ) 3 x 2 4 x 5 = - + Polynomial. Degree 2. (b) Not a polynomial. (c) Not a polynomial.

71 If f is a polynomial function and r is a real number for which f(r)=0, then r is called a (real) zero of f, or root of f(x) = 0. If r is a (real) zero of f, then (a) r is an x-intercept of the graph of f. (b) (x - r) is a factor of f.

72 Use the above to conclude that x = -1 and x = 4 are the real roots (zeroes) of f.

73 1 is a zero of multiplicity 2.

74 . If r is a Zero of Even Multiplicity
If r is a Zero of Odd Multiplicity .

75 Theorem If f is a polynomial function of degree n, then f has at most n-1 turning points.

76 Theorem For large values of x, either positive or negative, the graph of the polynomial resembles the graph of the power function.

77 For the polynomial (a) Find the x- and y-intercepts of the graph of f.
(b) Determine whether the graph crosses or touches the x-axis at each x-intercept. (c) Find the power function that the graph of f resembles for large values of x. (d) Determine the maximum number of turning points on the graph of f.

78 For the polynomial (e) Use the x-intercepts and test numbers to find the intervals on which the graph of f is above the x-axis and the intervals on which the graph is below the x-axis. (f) Put all the information together, and connect the points with a smooth, continuous curve to obtain the graph of f.

79 (b) -4 is a zero of multiplicity 1. (crosses)
(a) The x-intercepts are -1, 5 and -4. y-intercept: (b) -4 is a zero of multiplicity 1. (crosses) -1 is a zero of multiplicity 2. (touches) 5 is a zero of multiplicity 1. (crosses) (d) At most 3 turning points.

80 Test number: f (-5) Graph of f: Above x-axis Point on graph: (-5, 160)

81 Graph of f: Below x-axis
Test number: f (-2) = -14 Graph of f: Below x-axis Point on graph: (-2, -14)

82 Graph of f: Below x-axis
Test number: f (0) = -20 Graph of f: Below x-axis Point on graph: (0, -20)

83 Test number: f (6) = 490 Graph of f: Above x-axis Point on graph: (6, 490)

84 (6, 490) (-1, 0) (-5, 160) (0, -20) (5, 0) (-4, 0) (-2, -14)

85 Quadratic Functions

86 A quadratic function is a function of the form:

87 Properties of the Graph of a Quadratic Function
Parabola opens up if a > 0; the vertex is a minimum point. Parabola opens down if a < 0; the vertex is a maximum point.

88 Graphs of a quadratic function f(x) = ax2 + bx + c
Opens down Vertex is highest point Axis of symmetry a < 0 Axis of symmetry a > 0 Opens up Vertex is lowest point

89 Steps for Graphing a Quadratic Function by Hand
Determine the vertex. Determine the axis of symmetry. Determine the y-intercept, f(0). Determine how many x-intercepts the graph has. If there are no x-intercepts determine another point from the y-intercept using the axis of symmetry. Graph.

90 Since -3 < 0 the parabola opens down.
Without graphing, locate the vertex and find the axis of symmetry of the following parabola. Does it open up or down? Vertex: Since -3 < 0 the parabola opens down.

91 Finding the vertex by completing the square:
= a(x - h)2 + k; vertex: (2, 13)

92 (2,4) (0,0)

93 (0,0) (2, -12)

94 (2, 0) (4, -12)

95 Vertex (2, 8) (4,-4) f(x) = -3( x - 2 )2 + 8

96 Determine whether the graph opens up or down.
Find its vertex, axis of symmetry, y-intercept, x-intercept. x-coordinate of vertex: y-coordinate of vertex: Axis of symmetry:

97 There are two x-intercepts:

98 (0, 5) (-5.55, 0) (-0.45, 0) Vertex: (-3, -13)

99 Quadratic Models

100 A farmer has 3000 yards of fence to enclose a rectangular field
A farmer has 3000 yards of fence to enclose a rectangular field. What are the dimensions of the rectangle that encloses the most area? w x The available fence represents the perimeter of the rectangle. If x is the length and w the width , then 2x + 2w = 3000

101 The area of a rectangle is represented by
A = xw Let us express one of the variables from the perimeter equation. 2x + 2w = 3000 x = (3000-2w)/2 x = w Substitute this into the area equation and maximize for w. A = (1500-w)w = -w w The equation represents a parabola that opens down, so it has a maximum at its vertex point.

102 The vertex is w = -1500/(-2) = 750. Thus the width should be 750 yards and the length is then x = = 750 The largest area field is the one with equal sides of length 750 yards and total area: A = 7502=562,500 sq.y.

103 A projectile is fired from a cliff 400 feet above the water at an inclination of 45o to the horizontal, with a given muzzle velocity of 350ft per second. The height of the projectile above water is given by the equation below where x represents the horizontal distance of the projectile from the base of the cliff. Find the maximum height of the projectile.

104 To find the maximum height we need to find the coordinates of the vertex of the parabola that is represented by the above equation.

105 The maximum height is feet and the projectile reaches it at feet from the base of the cliff.

106 Vertex ( , ) (0,400)

107 Rational Functions I

108 A rational function is a function of the form
Where p and q are polynomial functions and q is not the zero polynomial. The domain consists of all real numbers except those for which the denominator is 0.

109 All real numbers except -6 and-2.
Find the domain of the following rational functions: All real numbers except -6 and-2. All real numbers except -4 and 4. All real numbers.

110

111 y Horizontal Asymptotes y = R(x) y = L x y y = L x y = R(x)

112 Vertical Asymptotes x = c y x x = c y x

113 If an asymptote is neither horizontal nor vertical it is called oblique.
x

114 Theorem Locating Vertical Asymptotes
A rational function in lowest terms, will have a vertical asymptote x = r, if x - r is a factor of the denominator q.

115 Vertical asymptotes: x = -1 and x = 1
Find the vertical asymptotes, if any, of the graph of each rational function. Vertical asymptotes: x = -1 and x = 1 No vertical asymptotes Vertical asymptote: x = -4

116 Consider the rational function
1. If n < m, then y = 0 is a horizontal asymptote of the graph of R. 2. If n = m, then y = an / bm is a horizontal asymptote of the graph of R. 3. If n = m + 1, then y = ax + b is an oblique asymptote of the graph of R. Found using long division. 4. If n > m + 1, the graph of R has neither a horizontal nor oblique asymptote. End behavior found using long division.

117 Find the horizontal and oblique asymptotes if any, of the graph of
Horizontal asymptote: y = 0 Horizontal asymptote: y = 2/3

118 Oblique asymptote: y = x + 6

119 Rational Functions II: Analyzing Graphs

120 Analyzing the Graph of a Rational Function
Find the domain of the rational function R. Write R in the lowest terms. Locate the x and y intercepts. Test for symmetry. Locate vertical asymptotes. Locate horizontal and oblique asymptotes. Graph R.

121 Analyze the graph of:

122 In lowest terms: x-intercept: -1 y-intercept: No symmetry

123 Vertical asymptote: x = -3
Hole: (3, 4/3) Horizontal asymptote: y = 2

124 1 -4 -2 R(1) = 1 R(-4) = 6 R(-2) = -2 Above x-axis Above x-axis Below x-axis (-4, 6) (-2, -2) (1, 1)

125 x = - 3 (-4, 6) (1, 1) (3, 4/3) y = 2 (-2, -2) (-1, 0) (0, 2/3)

126 Exponential Functions

127 An exponential function is a function of the form
where a is a positive real number (a > 0) and The domain of f is the set of all real numbers.

128 (1, 6) (1, 3) (-1, 1/6) (-1, 1/3) (0, 1)

129 Summary of the characteristics of the graph of
The domain is all real numbers. Range is set of positive numbers. No x-intercepts; y-intercept is 1. The x-axis (y=0) is a horizontal asymptote as a>1, is an increasing function and is one-to-one. The graph contains the points (0,1); (1,a), and (-1, 1/a). The graph is smooth continuous with no corners or gaps.

130 (-1, 6) (-1, 3) (0, 1) (1, 1/3) (1, 1/6)

131 Summary of the characteristics of the graph of
The domain is all real numbers. Range is set of positive numbers. No x-intercepts; y-intercept is 1. The x-axis (y=0) is a horizontal asymptote as 0<a<1, is a decreasing function and is one-to-one. The graph contains the points (0,1); (1,a), and (-1, 1/a). The graph is smooth continuous with no corners or gaps.

132

133 (1, 3) (0, 1)

134 (-1, 3) (0, 1)

135 (-1, 5) (0, 3) y = 2

136 Domain: All real numbers
Range: { y | y >2 } or Horizontal Asymptote: y = 2

137 The number e is defined as the number that the expression
In calculus this expression is expressed using limit notation as

138

139

140 Exponential Equations

141 Solve:

142 Logarithmic Functions

143

144 Change exponential expression into an equivalent logarithmic expression.
Change logarithmic expression into an equivalent exponential expression.

145 Range of Logarithmic and Exponential Functions
Domain of logarithmic function = Range of exponential function = Range of logarithmic function = Domain of exponential function =

146 y = x (0, 1) (1, 0) a < 1

147 y = x (0, 1) (1, 0) a > 1

148 1. The x-intercept of the graph is 1. There is no y-intercept.
Properties of the Graph of a Logarithmic Function 1. The x-intercept of the graph is 1. There is no y-intercept. 2. The y-axis is a vertical asymptote of the graph. 3. A logarithmic function is decreasing if < a < 1 and increasing if a > 1. 4. The graph is smooth and continuous, with no corners or gaps.

149 The Natural Logarithm

150

151 (e, 1) (1, 0)

152 x = 3 (e + 3, 1) (4, 0)

153

154 The Common Logarithmic Function
(base=10)

155 Logarithmic Equations

156 Logarithmic and Exponential Equations

157

158 Check your answer!

159 Both terms are undefined.
Check x = 3. Solution set {x | x = 3}.

160

161 Equation of Quadratic Type

162 3 x = -10 3 x = 1 = 3 0 No solution. Solution x = 0.
Solution set {x | x =0}.

163

164 x

165 x =

166 [STEP FUNCTION]

167 The greatest integer function (or floor function or step function) will round any number down to the nearest integer. It is the greatest integer less than or equal to x and is denoted by [x]. For example, [2.001] =2, [2.998] = 2 and [-2.567] = -3

168 The domain of y = [x] is R and range is Z
Graph of y = [x]

169 Polynomial and Rational Inequalities

170 Steps for Solving Polynomial and Rational Inequalities Algebraically
Write the inequality in one of the following forms: where f(x) is written as a single quotient. Determine the numbers at which f(x) equals zero and also those numbers at which it is undefined.

171 Use these numbers to separate the real line into intervals.
Select a test number from each interval and evaluate f at the test number. If the value of f is positive, then f(x)> 0 for all numbers x in the interval. If the value of f is negative, then f(x)<0 for all numbers x in the interval. If the inequality is not strict, include the solutions of f(x)=0 in the solution set, but do not include those where f is undefined.

172 Undefined for Solve the inequality:
The inequality is in lowest terms, so we will first find where f(x)=0. And where is it undefined. Undefined for x=-2

173 The real line is split into:

174 The solution is all numbers x for which
Pick x = - 3 Pick x = 0 Pick x = 2 Pick x = -3/2 f(-3) = -8 f(-3/2) = 5/2 f(0) = -1/2 f(2) = 3/4 POSITIVE NEGATIVE POSITIVE NEGATIVE The solution is all numbers x for which or

175 Operations on Functions

176 The sum f + g is the function defined by
(f + g)(x) = f(x) + g(x) The domain of f+g consists of numbers x that are in the domain of both f and g.

177 The difference f - g is the function defined by
(f - g)(x) = f(x) - g(x) The domain of f - g consists of numbers x that are in the domain of both f and g.

178 The product f *g is the function defined by
(f * g)(x) = f(x) * g(x) The domain of f *g consists of numbers x that are in the domain of both f and g.

179

180 Given two functions f and g, the composite function is defined by

181 Domain of g Range of g Range of f x g(x) Domain of f g(x) x f(g(x)) g f Range of f(g) f(g)

182 In general

183

184

185

186 Domain: x > 1

187

188 Symmetry; Graphing Key Equations

189 Symmetry A graph is said to be symmetric with respect to the x-axis
if for every point (x,y) on the graph, the point (x,-y) is on the graph.

190 symmetric with respect to the y-axis
A graph is said to be symmetric with respect to the y-axis if for every point (x,y) on the graph, the point (-x,y) is on the graph.

191 symmetric with respect to the origin
A graph is said to be symmetric with respect to the origin if for every point (x,y) on the graph, the point (-x,-y) is on the graph.

192 Tests for Symmetry x-axis Replace y by -y in the equation. If an equivalent equation results, the graph is symmetric with respect to the x-axis. y-axis Replace x by -x in the equation. If an equivalent equation results, the graph is symmetric with respect to the y-axis. origin Replace x by -x and y by -y in the equation. If an equivalent equation results, the graph is symmetric with respect to the origin.

193 Not symmetric with respect to the x-axis.

194 Symmetric with respect to the y-axis.

195 Not symmetric with respect to the origin.

196 Graphing Techniques; Transformations

197

198 (2, 6) (1, 3) (2, 4) (1, 1) (0, 2) (0, 0)

199

200 (2, 4) (0, 0) (1, 1) (2, 1) (1, -2) (0, -3)

201 Vertical Shifts c> The graph of f(x) + c is the same as the graph of f(x) but shifted UP by c. For example: c = 2 then f(x) + 2 shifts f(x) up by 2. c< The graph of f(x) + c is the same as the graph of f(x) but shifted DOWN by c. For example: c = -3 then f(x) + (-3) = f(x) - 3 shifts f(x) down by 3.

202

203

204 Horizontal Shifts If the argument x of a function f is replaced by
x - h, h a real number, the graph of the new function y = f( x - h ) is the graph of f shifted horizontally left (if h < 0) or right (if h > 0).

205

206

207 Reflections about the x-Axis and the y-Axis
The graph of g= - f(x) is the same as graph of f(x) but reflected about the x-axis. The graph of g= f(-x) is the same as graph of f(x) but reflected about the y-axis.

208

209

210

211

212

213

214 Compression and Stretches
The graph of y = af(x) is obtained from the graph of y = f(x) by vertically stretching the graph if a > 1 or vertically compressing the graph if 0 < a < 1. The graph of y= f(ax) is obtained from the graph of y = f(x) by horizontally compressing the graph if a > 1 or horizontally stretching the graph if 0 < a < 1.

215

216 GRAPHS OF TRIGONOMETRIC FUNCTIONS

217 The function y = sin x has period 2π, because sin (x + 2π) = sin x.
Here is the graph of y = sin x:                                                                                                                     The function  y = sin x  has period 2π, because sin (x + 2π) = sin x.

218 The graph of y = sin ax When a function has this form, y = sin ax, then the constant a indicates the number of periods in an interval of length 2π. For example, if a = 2, then, y = sin 2x -- that means there are 2 periods in an interval of length 2π.                                                                                                                                   If a = 3 , then y = sin 3x -- there are 3 periods in that interval:

219 The graph of y = cos x                                                                                                                                                                                                                                                    The graph of y = tan x

220 Students are advised to draw the graphs of other
Trigonometric functions


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