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Published byGeorgiana Ray Modified over 9 years ago
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Essential Question: How can you determine if x-2 is a factor of a polynomial without factoring?
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Standard Form ◦ Largest Exponent comes first. ◦ Combine like terms (if possible) ◦ The constant (number without a variable) comes last Example ◦ Write the following polynomials in standard form -7x + 5x 4 x 2 – 4x + 3x 3 + 2x 5x 4 – 7x 3x 3 + x 2 – 2x
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Degree ◦ The degree of a polynomial is the largest exponent Example ◦ Find the degree of the polynomial 5x 4 - 7x Quartic Cubic DegreeName Using DegreeExample 0Constant6 1Linearx + 3 2Quadratic3x 2 3Cubic2x 3 – 5x 2 – 2x 4Quarticx 4 + 3x 2 5Quintic-2x 5 + 3x 2 – x + 4 3x 3 + x 2 - 2x
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Number of Terms Example ◦ Classify each polynomial by the number of terms 5x 4 - 7x Binomial Trinomial Number of Terms Name using Number of Terms Example 1Monomial6 2Binomialx + 3 3Trinomial2x 3 – 5x 2 – 2x More than 3Polynomial of x terms-2x 5 + 3x 2 – x + 4 3x 3 + x 2 - 2x
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Write the expression (x + 1)(x + 2)(x + 3) as a polynomial in standard form. ◦ FOIL the last two terms (x + 1)(x + 2)(x + 3) (x + 1)(x 2 + 3x + 2x + 6) (x + 1)(x 2 + 5x + 6) ◦ Distribute the (x + 1) to all terms (x + 1)(x 2 + 5x + 6) x 3 + 5x 2 + 6x + x 2 + 5x + 6 ◦ Combine like terms x 3 + 6x 2 + 11x + 6
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Y OUR TURN Write the expression (x + 1)(x + 1)(x + 2) as a polynomial in standard form. (x + 1)(x + 1)(x + 2) (x + 1)(x 2 + 2x + 1x + 2) (x + 1)(x 2 + 3x + 2) x 3 + 3x 2 + 2x + x 2 + 3x + 2 x 3 + 4x 2 + 5x + 2
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Writing a Polynomial in Factored Form ◦ Write 2x 3 + 10x 2 + 12x in factored form ◦ Factor out a GCF first 2x 3 + 10x 2 + 12x 2x(x 2 + 5x + 6) ◦ Factor the quadratic in parenthesis 2x(x + 2)(x + 3)
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Y OUR TURN Write 3x 3 – 3x 2 – 36x in factored form 3x(x 2 – x – 12) 3x(x – 4)(x + 3)
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Assignment ◦ Page 309 Problems 1 – 11 (odd problems) Make sure to include the original problem ◦ Page 317 Problems 1 – 6 (all problems) Problems 7 – 11 (odd problems) Show your work Remember: (x – 3) 2 means (x – 3)(x – 3), not x 2 + 9
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Essential Question: How can you determine if x-2 is a factor of a polynomial without factoring?
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If a polynomial is in factored form, you can use the Zero Product Property to find values that will make the polynomial equal zero. Example ◦ Find the zeros of y = (x – 2)(x + 1)(x + 3). ◦ Just like factoring, if any of the parenthesis come out as zero, then the function is zero. x – 2 = 0orx + 1 = 0orx + 3 = 0 x + 2 = +2x – 1 = -1x – 3 = -3 -2 x = 2+1 x = -1+3 x = -3 Your Turn ◦ Find the zeros of the function y = (x – 7)(x – 5)(x – 3) ◦ x = 7, 5, or 3
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Writing a Polynomial Function From Its Zeros ◦ Write a polynomial function in standard form with zeros at -2, 3 and 3 ◦ Just the opposite of what we did in the last example, except we also have to multiply the factors together (x + 2)(x – 3)(x – 3) FOIL the last two terms (x + 2)(x 2 – 6x + 9) Distribute the x + 2 to all terms x 3 – 6x 2 + 9x + 2x 2 – 12x + 18 Combine like terms x 3 – 4x 2 – 3x + 18
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Y OUR TURN Write a polynomial function in standard form with zeros at -4, -2 and 1 (x + 4)(x + 2)(x - 1) (x + 4)(x 2 – 1x + 2x - 2) (x + 4)(x 2 + x - 2) x 3 + x 2 – 2x + 4x 2 + 4x - 8 x 3 + 5x 2 + 2x – 8
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Multiplicity ◦ Sometimes, a zero can show up multiple times. Though we generally don’t list multiple zeros as solutions, a multiple zero has MULTIPLICITY equal to the number of times the zero occurs. ◦ Example: f(x) = x 4 + 6x 3 + 8x 2 f(x) = x 2 (x 2 + 6x + 8) f(x) = x 2 (x + 4)(x + 2) Note: you can rewrite x 2 as (x – 0) 2 or (x – 0)(x – 0) The zeros are x = 0 (multiplicity 2), x = -4, and x = -2
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FFind the zeros of the function. State any multiplicity of multiple zeros. ◦f◦f(x) = (x – 2)(x - 1)(x + 1) 2 xx = 2, x = 1, x = -1 (multiplicity 2) ◦y◦y = x 3 – 4x 2 + 4x yy = x(x 2 – 4x + 4) yy = x(x – 2)(x – 2) xx = 0, x = 2 (multiplicity 2)
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Assignment ◦ Page 317 - 318 Problems 16 – 27 (all problems) Problems 29 – 35, 41 – 45 (odd problems) Show your work (not relevant in 16-20) Don’t graph problems 16 - 20
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