Do Now Given the polynomial 8 -17x3+ 16x - 20x4 - 8 Write the polynomial in standard form: __________ Classify the polynomial by degree: _______________________________________ Classify the polynomial by the number of terms: ________________________________ State the End Behavior: ________________________________ - 20x4 -17x3 +16x Quartic Trinomial Down and Down

5.2 Polynomials, Linear Factors, and Zeros Learning Target: I can find the zeros of a polynomial function and I can write the function from its zeros Learning Target: I can find the zeros of a polynomial function and I can write the function from its zeros

Polynomials and Real Roots Relative Maximum Let’s Review Roots Zeros Solutions X-Intercepts Relative Maximum Relative Minimum Relative Minimum ROOTS ! LT: I can find the zeros of a polynomial function and I can write the function from its zeros L.

Linear Factors Just as you can write a number into its prime factors (jail trick: Example 6 into 2 & 3) you can write a polynomial into its linear factors. (factoring) x2 + 4x – 12 into (x+6)(x-2)

 Important Linear Factors Take some private time and try factoring the following so we can find the zeros: 2x3 + 8x2 – 24x = 0 Factor out the GCF 2x(x2 + 4x – 12) = 0 Factor the Quadratic 2x(x-6)(x+2) = 0 Use the Zero Product Property x = 0, 6 or -2  Important

We can also take a polynomial in factored form and rewrite it into standard form. Take a minute on your own and try to distribute Ex. (x+1)(x+2)(x+3) = foil distribute (x2+5x+6)(x+1)=x (x2+5x+6)+1 (x2+5x+6) = x3+6x2+11x+6 Standard form  Book way  My way x2 5x 6 X x3 5x2 6x 1

Vocabulary Alert. A repeated zero is called a multiple zero Vocabulary Alert! A repeated zero is called a multiple zero. A multiple zero has a multiplicity equal to the number of times the zero occurs. On a graph, a double zero “bounces” off the x axis. (the parent quadratic) A triple zero “flattens out” as it crosses the x axis. (the parent cubic)

Zeros A zero is a (solution or x-intercept) to a polynomial function. Zero Product Property If (x – a) is a factor of a polynomial, then a is a zero (solution) of the function. If a polynomial has a repeated solution, it has a multiple zero. The number of repeats of a zero is called its multiplicity.

Zeros Copy down the equation: (x+1)(x-7)(x-2) What are the zero’s? If we use the zero product property we get: X= -1, 7 or 2

Vocab!! What is Multiplicity? Multiplicity is when you have multiple roots that are exactly the same. We say that the multiplicity is how many duplicate roots that exist. Ex: (x-2)(x-2)(x+3) Ex: (x-1)4 (x+3) Ex: y =x(x-1)(x+3) Note: two answers are x=2; therefore the multiplicity is 2 Note: four answers are x=1; therefore the multiplicity is 4 Note: there are no repeat roots, so we say that there is no multiplicity

Polynomials and Linear Factors Write a polynomial in standard form with zeros at 2, –3, and 0. 2 –3 0 Zeros ƒ(x) = (x – 2)(x + 3)(x) Write a linear factor for each zero. = (x – 2)(x2 + 3x) Multiply (x + 3)(x). = x(x2 + 3x) – 2(x2 + 3x) Distributive Property = x3 + 3x2 – 2x2 – 6x Multiply. = x3 + x2 – 6x Simplify. The function ƒ(x) = x3 + x2 – 6x has zeros at 2, –3, and 0. LT: I can find the zeros of a polynomial function and I can write the function from its zeros

Write a polynomial given the roots 0, -3, 3 Put in factored form y = (x – 0)(x + 3)(x – 3) y = (x)(x + 3)(x – 3) y = x(x² – 9) y = x³ – 9x L.T. I can analyze the factored form of a polynomial and write function from its zeros

Graph / Sketch Y = (x-2)(x+9)(x+2) We know there are zeros at? Can you describe the end behavior? How many turns are there? Sketch it!

Assignment #7 Friday pg 293 9-33 by 3’s Do not Graph Monday Graph when instructed

Write a polynomial given the roots 2, -4, ½ Note that the ½ term becomes (x-1/2). We don’t like fractions, so multiply both terms by 2 to get (2x-1) Put in factored form y = (x – 2)(x + 4)(2x – 1) y = (x² + 4x – 2x – 8)(2x – 1) y = (x² + 2x – 8)(2x – 1) y = 2x³ – x² + 4x² – 2x – 16x + 8 y = 2x³ + 3x² – 18x + 8 L.T. I can analyze the factored form of a polynomial and write function from its zeros

Write the polynomial in factored form. Then find the roots Write the polynomial in factored form. Then find the roots. Y = 3x³ – 27x² + 24x Y = 3x³ – 27x² + 24x Y = 3x(x² – 9x + 8) Y = 3x(x – 8)(x – 1) ROOTS? 3x(x – 8)(x – 1) = 0 Roots = 0, 8, 1 FACTORED FORM L.T. I can analyze the factored form of a polynomial and write function from its zeros

Let’s Try One Find any multiple zeros of f(x)=x4+6x3+8x2 and state the multiplicity L.T. I can analyze the factored form of a polynomial and write function from its zeros

Let’s Try One Find any multiple zeros of f(x)=x4+6x3+8x2 and state the multiplicity L.T. I can analyze the factored form of a polynomial and write function from its zeros

Equivalent Statements about Polynomials -4 is a solution of x2+3x-4=0 -4 is an x-intercept of the graph of y=x2+3x-4 -4 is a zero of y=x2+3x-4 (x+4) is a factor of x2+3x-4 These all say the same thing L.T. I can analyze the factored form of a polynomial and write function from its zeros

Polynomials and Linear Factors Find any multiple zeros of ƒ(x) = x5 – 6x4 + 9x3 and state the multiplicity. ƒ(x) = x5 – 6x4 + 9x3 ƒ(x) = x3(x2 – 6x + 9) Factor out the GCF, x3. ƒ(x) = x3(x – 3)(x – 3) Factor x2 – 6x + 9. Since you can rewrite x3 as (x – 0)(x – 0)(x – 0), or (x – 0)3, the number 0 is a multiple zero of the function, with multiplicity 3. Since you can rewrite (x – 3)(x – 3) as (x – 3)2, the number 3 is a multiple zero of the function with multiplicity 2. L.T. I can analyze the factored form of a polynomial and write function from its zeros

Example We can rewrite a polynomial from its zeros. Write a poly with zeros -2, 3, and 3 f(x)= (x+2)(x-3)(x-3) foil = (x+2)(x2 - 6x + 9) now distribute to get = x3 - 4x2 - 3x + 18 this function has zeros at -2,3 and 3 L.T. I can analyze the factored form of a polynomial and write function from its zeros

Finding local Maximums and Minimum Find the local maximum and minimum of x3 + 3x2 – 24x Enter equation into calculator Hit 2nd Trace Choose max or min Choose a left and right bound and tell calculator to guess L.T. I can analyze the factored form of a polynomial and write function from its zeros

We can use the GCF (greatest common factor) to factor a poly in standard form into its linear factors. Ex. 2x3+10x2+12x GCF is 2x so factor it out. We get 2x(x2+5x+6) now factor once more to get 2x(x+2)(x+3) Linear Factors L.T. I can analyze the factored form of a polynomial and write function from its zeros

Theorem The expression (x - a) is a linear factor of a polynomial if and only if the value a is a zero (root) of the related polynomial function. If and only if = the theorem goes both ways If (x – a) is a factor of a polynomial, then a is a zero (solution) of the function. and Ifa is a zero (solution) of the function then (x – a) is a factor of a polynomial, L.T. I can analyze the factored form of a polynomial and write function from its zeros