Question

What are two numbers that equal 15 and -8? THIS IS 27 POINTS thank you!

Answer 1

-3 and -5

Explanation:

Why it is, is you are putting your equation into two separate parts.

(r-__)(r-__). That will give you the r^2.

You then have to think of the -8 and the 15. When you times -3 and -5 together you get 15, and if you add it together you get -8.

So it will be (r-3)(r-5).

How this is, is you will do FOIL.

F=FRONT. You do the r's to get r^2.

O=OUTER. You add the r and the -5 (which are the outer) to get -5.

I=INNER. You add the other r and the -3 (which are the inner) to get -3.

L=LAST. You times the -3 and the -5 (which are last) to get 15.

You then put it together to get r^2-8r+15=0.

So your answers are -3 and -5.

Answer 2

r=5 r=3

Explanation:

r^2 -8r+15 = 0

What 2 numbers multiply together to equal 15 and add together to equal -8

-5*-3 = 15

-5+-3 = -8

(r-5) (r-3) =0

Using the zero product property

r-5 = 0 r-3=0

r=5 r=3