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

(x+2)

Step-by-step explanation:

Our expression must be multiplied by another factor to make the needed equation, so lets multiply our factor by another factor where we use as a variable of the factor we don't know. We can now expand this and compare coefficients to try to determine our value for .

The terms of the coefficients for each expression must be the same, so we can say that

and

Solving both equations give us the same result,  

So we can use this to create a factor.

what does this expand to give us?

this is correct!