Question

If x – 10 is a factor of x2 – 8x – 20, what is the other factor?

Answer 1

X^2−8x−20x^2−8x−20=(x+2)(x−10)
So the other factor is (x+2)
Cheers,Irys

Answer 2

Answer:

The other factor is $(x+2)$

Step-by-step explanation:

we know that

$(x-a)(x-b)=x^{2}-xb-xa+ab$

$(x-a)(x-b)=x^{2}-(a+b)x+ab$

In this problem we have

$x^{2} -8x-20$

and

$a=10$ -----> because is a factor

substitute and solve for b

$x^{2} -8x-20=x^{2}-(10+b)x+10b$

so

$8=10+b\\b=-2$

Verify in the second equation

$-20=10b$ -----> $-20=10(-2)$ -----> $-20=-20$--> is ok

The other factor is $(x+2)$