Question

What expression is the factorization of x^2+10x+21

a: (x+3)(x+7)
b: (x+4)(x+6)
c: (x+6)(x+15)
d: (x+7)(x+14)

Answer 1

a

Explanation:

FOIL

f-first

o-outer

i-inner

l-last

Answer 2

(x+3)(x+7)

Explanation:

3+7 = 10 (the middle number)

3(7) = 21 (the third number)