Solve x^2 - 10x = - 21.

A. x = 7 and x = 3

B. x = - 7 and x = 3

C. x=-7 and x = - 3

D. x = 7 and x = - 3

A

Step-by-step explanation:

1. move - 21 over to the other side to get x^2 - 10x + 21

2. factor. you want to find something that multiples to 21 (the c value) but adds up to - 10 (the b value.) the numbers are - 7 and - 3. so you would factor it out like this: (x-7) (x-3)

3. set each factor to 0 to find the x values

x-7=0 and x-3=0. once you move the numbers over to isolate the x term, you should get x=7 and x=3.