Respuesta :

What multiplies to 21 that also adds up to 10? 7 and 3 would be your answer.
So, the expression (x + 7)(x + 3) is the factorization of x2+10x+21
To see if this answer is correct, FOIL it:
x2+3x+7x+21
x2+10x+21
Hope I helped!