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6. keith determines the zeros of the function f(x) to be -6 and 5. what…

Question

  1. keith determines the zeros of the function f(x) to be -6 and 5. what could be keith’s function?

a. $f(x) = x + 5)(x + 6)$
b. $f(x) = (x + 5)(x - 6)$
c. $f(x) = (x - 5)(x + 6)$
d. $f(x) = (x - 5)(x - 6)$

  1. the zeros of the function $f(x) = 2x^3 + 12x - 10x^2$ are

a. ${2, 3}$
b. ${-1, 6}$
c. ${0, 2, 3}$
d. ${0, -1, 6}$

  1. which polynomial function has the zeros at -3, 0 and 4?

a. $f(x) = (x + 3)(x^2 + 4)$
b. $f(x) = (x^2 - 3)(x - 4)$
c. $f(x) = x(x + 3)(x - 4)$
d. $f(x) = x(x - 3)(x + 4)$

  1. explain how to determine the zeros of $f(x) = (x + 3)(x - 1)(x - 8)$. state the zeros of the function.
  1. the graph of the function $f(x) = ax^2 + bx + c$ is given. could the factors of $f(x)$ be $(x + 2)$ and $(x - 3)$? based on the graph, explain why or why not.

graph of a parabola opening upwards, vertex on the y-axis, crossing the x-axis at two points symmetric about the y-axis

Explanation:

Question 6

Step1: Recall zero - factor property

If a function \(y = f(x)\) has a zero at \(x = a\), then \((x - a)\) is a factor of \(f(x)\).

Step2: Find factors for given zeros

The zeros of the function are \(x=-6\) and \(x = 5\).
For \(x=-6\), the factor is \((x-(-6))=(x + 6)\).
For \(x = 5\), the factor is \((x - 5)\).
So the function \(f(x)=(x - 5)(x + 6)\).

Step1: Rewrite the function

Given \(f(x)=2x^{3}+12x - 10x^{2}\), we first rewrite it in standard form (descending powers of \(x\)): \(f(x)=2x^{3}-10x^{2}+12x\).

Step2: Factor out the GCF

Factor out the greatest common factor \(2x\) from each term: \(f(x)=2x(x^{2}-5x + 6)\).

Step3: Factor the quadratic

Factor the quadratic \(x^{2}-5x + 6\). We need two numbers that multiply to \(6\) and add up to \(- 5\). The numbers are \(-2\) and \(-3\). So \(x^{2}-5x + 6=(x - 2)(x - 3)\).

Step4: Find the zeros

Set \(f(x)=0\), then \(2x(x - 2)(x - 3)=0\).
Using the zero - factor property:
\(2x=0\) gives \(x = 0\);
\(x - 2=0\) gives \(x = 2\);
\(x - 3=0\) gives \(x = 3\).
So the zeros are \(0\), \(2\) and \(3\).

Step1: Recall zero - factor property

If a function \(y = f(x)\) has a zero at \(x=a\), then \((x - a)\) is a factor of \(f(x)\).

Step2: Find factors for given zeros

The zeros are \(x=-3\), \(x = 0\) and \(x = 4\).
For \(x=-3\), the factor is \((x-(-3))=(x + 3)\).
For \(x = 0\), the factor is \(x\) (since when \(x = 0\), \(x=0\) implies the factor is \(x\)).
For \(x = 4\), the factor is \((x - 4)\).
So the function \(f(x)=x(x + 3)(x - 4)\).

Answer:

c. \(f(x)=(x - 5)(x + 6)\)

Question 7