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2.1 Evaluate and Graph Polynomial Functions Objectives: Identify, evaluate, add, and subtract polynomials Classify polynomials, and describe the shapes of their graphs
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What is a Polynomial? 1 or more terms Exponents are whole numbers (not a radical) Coefficients are all real numbers (no imaginary #’s) It is in Standard Form when the exponents are written in descending order.
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Definitions for Polynomials Monomial: a numeral, variable, or the product of a numeral and one or more variables Ex: Constant: a monomial w/ no variables Ex: Coefficient: numerical factor in a monomial Ex: Degree of a Monomial: sum of exponents of its variables Ex: See Below Give the degree for the following monomial. 4x 2 y 3 z _________ ab 4 c 2 ________ 8 ________ NOT QUOTIENT! i.e. “x” can’t be on bottom!!!! 6 7 0
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Polynomial: is many (more than 1) monomials connected by addition or subtraction. Definitions for Polynomials Binomial - ___________ Trinomial - ______________ Degree of the Polynomial: is the degree of it’s highest monomial term Example: Give the degree of the polynomial. 4x 3 + 6x 2 -8x 5 – 6 ________ (5x + 4)(2x 2 + 3x – 2)
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Classification of a Polynomial DegreeNameExample -2x 5 + 3x 4 – x 3 + 3x 2 – 2x + 6 n = 0 n = 1 n = 2 n = 3 n = 4 n = 5 constant 3 linear 5x + 4 quadratic 2x 2 + 3x - 2 cubic 5x 3 + 3x 2 – x + 9 quartic 3x 4 – 2x 3 + 8x 2 – 6x + 5 quintic
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Classify each polynomial by degree and by number of terms. a) 5x + 2x 3 – 2x 2 cubic trinomial b) x 5 – 4x 3 – x 5 + 3x 2 + 4x 3 quadratic monomial c) x 2 + 4 – 8x – 2x 3 d) 3x 3 + 2x – x 3 – 6x 5 cubic polynomial quintic trinomial e) 2x + 5x 7 7 th degree binomial Not a polynomial
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EXAMPLE 1 Identify polynomial functions 4 Decide whether the function is a polynomial function. If so, write it in standard form and state its degree, type, and leading coefficient. a. h (x) = x 4 – x 2 + 3 1 SOLUTION a. The function is a polynomial function that is already written in standard form. It has degree 4 (quartic) and a leading coefficient of 1.
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EXAMPLE 1 Identify polynomial functions Decide whether the function is a polynomial function. If so, write it in standard form and state its degree, type, and leading coefficient. b. g (x) = 7x – 3 + πx 2 SOLUTION b. The function is a polynomial function written as g(x) = πx 2 + 7x – 3 in standard form. It has degree 2 (quadratic) and a leading coefficient of π.
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EXAMPLE 1 Identify polynomial functions Decide whether the function is a polynomial function. If so, write it in standard form and state its degree, type, and leading coefficient. c. f (x) = 5x 2 + 3x –1 – x SOLUTION c. The function is not a polynomial function because the term 3x – 1 has an exponent that is not a whole number.
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EXAMPLE 1 Identify polynomial functions Decide whether the function is a polynomial function. If so, write it in standard form and state its degree, type, and leading coefficient. d. k (x) = x + 2 x – 0.6x 5 SOLUTION d. The function is not a polynomial function because the term 2 x does not have a variable base and an exponent that is a whole number.
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GUIDED PRACTICE for Examples 1 and 2 Decide whether the function is a polynomial function. If so, write it in standard form and state its degree, type, and leading coefficient. 1. f (x) = 13 – 2x polynomial function; f (x) = –2x + 13; degree 1, type: linear, leading coefficient: –2 2. p (x) = 9x 4 – 5x – 2 + 4 3. h (x) = 6x 2 + π – 3x polynomial function; h(x) = 6x 2 – 3x + π ; degree 2, type: quadratic, leading coefficient: 6 not a polynomial function
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EXAMPLE 2 Evaluate by direct substitution Use direct substitution to evaluate f (x) = 2x 4 – 5x 3 – 4x + 8 when x = 3. f (x) = 2x 4 – 5x 3 – 4x + 8 f (3) = 2(3) 4 – 5(3) 3 – 4(3) + 8 = 162 – 135 – 12 + 8 = 23 Write original function. Substitute 3 for x. Evaluate powers and multiply. Simplify
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GUIDED PRACTICE for Examples 1 and 2 Use direct substitution to evaluate the polynomial function for the given value of x. 4. f (x) = x 4 + 2x 3 + 3x 2 – 7; x = –2 5 ANSWER 5. g(x) = x 3 – 5x 2 + 6x + 1; x = 4 9 ANSWER
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Solving by Synthetic Substitution (Division) (x - 2) is a Factor of use x = 2 Use the Polynomials coefficients Multiply Answer Add Down Drop 1 st coefficient down Remainder if there is any The Solution starts with one degree less than original
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HomeworkHomework Pg.69 1 – 20
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