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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.

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Presentation on theme: "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."— Presentation transcript:

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5 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. 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.

6 DOMAIN RANGE X Y f x x x y y

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

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

9 Find the domain of the following functions: A) B)

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

11 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.

12 x y Not a function.

13 x y Function.

14 (0, -3) (2, 3) (4, 0) (10, 0) (1, 0)x Domain of a function represents the horizontal spread of its graph & the range the vertical spread.

15 One-to-One Function On-to Function Inverse Function

16 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.

17 x1x1 x2x2 x3x3 y1y1 y2y2 y3y3 Domain Co domain x1x1 x2x2 x3x3 y1y1 y3y3 Domain Co domain One-to-one & on-to function One-one but not on to function NOT One-to-one but on to function Domain Co domain

18 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

19 BIJECTIVE FUNCTION A function is said to be objective if it is both one-one and on-to x1x1 x2x2 x3x3 y1y1 y2y2 y3y3 Domain Co domain

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

21 Use the graph to determine whether the function is one-to-one. One-to-one.

22 . 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.

23 Domain of fRange of f

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

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

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

27 Check.

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30 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).

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

32 f(x) = x 2,Evenf(x) = x 3, Odd

33 y = cosx, Even y = sinx, Odd

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

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

36 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

37 PERIODIC FUNCTIONS

38 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.

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

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

41 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.

42 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 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.

43 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

44 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

45 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(4-3x 2 ) is not periodic

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

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

48 A function f(x) is said to be increasing in an interval, if for any x 1, x 2 belonging to this interval, x 1 < x 2 implies f(x 1 ) ≤ f(x 2 ) OR x 1 >x 2 implies f(x 1 ) ≥ f(x 2 ) 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 x 1 < x 2 implies f(x 1 ) < f(x 2 ) OR x 1 >x 2 implies f(x 1 ) > f(x 2 )

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50 The function y = 3 x is strictly increasing

51 A function f(x) is said to be DECREASING in an interval, if for any x 1, x 2 belonging to this interval, x 1 < x 2 implies f(x 1 ) ≥ f(x 2 ) OR x 1 > x 2 implies f(x 1 ) ≤ f(x 2 ) 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 x 1 f(x 2 ) OR x 1 >x 2 implies f(x 1 ) < f(x 2 )

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

53 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.

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

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

56 Library of Functions, Piecewise-Defined Functions

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

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

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

60 The square function

61 Cube Function

62 Square Root Function

63 Reciprocal Function

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

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

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

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

68 c)

69 Polynomial Functions and Models

70 A polynomial function is a function of the form

71 fxxx()  Polynomial. Degree 2. Not a polynomial. Determine which of the following are polynomials. For those that are, state the degree. (a) (b) (c)

72 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.

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

74 1 is a zero of multiplicity is a zero of multiplicity is a zero of multiplicity 5.

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

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

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

78 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.

79 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.

80 (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. (a) The x-intercepts are -1, 5 and -4. y-intercept:

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

82 Test number: -2 f (-2) = -14 Graph of f: Below x-axis Point on graph: (-2, -14) -4 < x < -1

83 Test number: 0 f (0) = -20 Graph of f: Below x-axis Point on graph: (0, -20) -1 < x < 5

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

85 (6, 490) (5, 0) (0, -20) (-1, 0) (-2, -14)(-4, 0) (-5, 160)

86 Quadratic Functions

87 A quadratic function is a function of the form:

88 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.

89 a > 0 Opens up Vertex is lowest point Axis of symmetry Graphs of a quadratic function f(x) = ax 2 + bx + c a < 0 Opens down Vertex is highest point Axis of symmetry

90 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.

91 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.

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

93 (0,0) (2,4)

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

95 (2, 0) (4, -12)

96 (2, 8) Vertex f(x) = -3( x - 2 ) (4,-4)

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

98 There are two x-intercepts:

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

100 Quadratic Models

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

102 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.

103 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 = =562,500 sq.y.

104 A projectile is fired from a cliff 400 feet above the water at an inclination of 45 o 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.

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

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

107 Vertex ( , ) (0,400)

108 Rational Functions I

109 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.

110 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.

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

113 x = c y x y x Vertical Asymptotes

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

115 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.

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

117 1. If n < m, then y = 0 is a horizontal asymptote of the graph of R. 2. If n = m, then y = a n / b m 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. Consider the rational function

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

119 Oblique asymptote: y = x + 6

120 Rational Functions II: Analyzing Graphs

121 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.

122 Analyze the graph of:

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

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

125 -4 R(-4) = 6 Above x-axis (-4, 6) -2 R(-2) = -2 Below x-axis (-2, -2) 1 R(1) = 1 Above x-axis (1, 1)

126 (-4, 6) (-2, -2) (-1, 0)(0, 2/3) (1, 1)(3, 4/3) y = 2 x = - 3

127 Exponential Functions

128 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.

129 (0, 1) (1, 3) (1, 6) (-1, 1/3) (-1, 1/6)

130 Summary of the characteristics of the graph of a >1 The domain is all real numbers. Range is set of positive numbers. No x-intercepts; y-intercept is 1. 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. The x-axis (y=0) is a horizontal asymptote as

131 (-1, 3) (-1, 6) (0, 1)(1, 1/3)(1, 1/6)

132 Summary of the characteristics of the graph of 0

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134 (0, 1) (1, 3)

135 (0, 1) (-1, 3)

136 (0, 3) (-1, 5) y = 2

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

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

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141 Exponential Equations

142 Solve:

143 Logarithmic Functions

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

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

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

148 (1, 0) (0, 1) a > 1 y = x

149 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 The graph is smooth and continuous, with no corners or gaps. Properties of the Graph of a Logarithmic Function

150 The Natural Logarithm

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152 (1, 0) (e, 1)

153 (4, 0) (e + 3, 1) x = 3

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155 The Common Logarithmic Function (base=10)

156 Logarithmic Equations

157 Logarithmic and Exponential Equations

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159 Check your answer!

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

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162 Equation of Quadratic Type

163 No solution. Solution x = 0. Solution set {x | x =0}. 3 x = x = 1 = 3 0

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165 x

166 x =

167 [STEP FUNCTION]

168 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

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

170 Polynomial and Rational Inequalities

171 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.

172 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.

173 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

174 The real line is split into:

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

176 Operations on Functions

177 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.

178 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.

179 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.

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

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

183 In general

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187 Domain: x > 1

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189 Symmetry; Graphing Key Equations

190 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.

191 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.

192 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.

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

194 Not symmetric with respect to the x-axis.

195 Symmetric with respect to the y-axis.

196 Not symmetric with respect to the origin.

197 Graphing Techniques; Transformations

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199 (0, 0) (1, 1) (2, 4) (0, 2) (1, 3) (2, 6)

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201 (0, 0) (1, 1) (2, 4) (0, -3) (1, -2) (2, 1)

202 Vertical Shifts c>0 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<0 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.

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205 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).

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208 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.

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215 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.

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217 GRAPHS OF TRIGONOMETRIC FUNCTIONS

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

219 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:

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

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


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