Respuesta :
Answer:
(x + 3)(x + 7).
Step-by-step explanation:
x^2 + 10x + 21.
You need 2 numbers whose product is the last number in the function (+21) and whose sum is the coefficient of x (+10).
These are + 3 and + 7, so the factors are:
(x + 3)(x + 7).
