Question

Consider the graph of the quadratic function y =

Answer 1

Answer:

A. -8 and 20

Step-by-step explanation:

I think your question is missed of key information, allow me to add in and hope it will fit the original one.  

Consider the graph of the quadratic function y = $\frac{1}{4}$$x^{2} - 3x - 40$

What are the roots of the function?

A. –8 and 20

B. –40 and –8

C. –8 and 8

D. –40 and 20

My answer:

Given the function:

y = $\frac{1}{4}$$x^{2} - 3x - 40$

<=> y = $x^{2} - 12x - 160$

Let convert to the factors form, the roots of the function must meet the following requirements:

• The two number that has the sum of 12 = -b
• The two number that has the product of -40 = c

In 4 possible answer, only –8 and 20  is possible because:

-8 + 20 = 12 = -b

-8*20 = -160 = c

So the factored form of the function is:

y = (x + 8)(x-20)

Hope it will find you well.