Which expression is the factorization of x2 + 10x + 21?

(x + 3)(x + 7)
(x + 4)(x + 6)
(x + 6)(x + 15)
(x + 7)(x + 14)

 First option is correct.

Step-by-step explanation:

Since we have given that

By using "Split the middle term ":,

Take the two integers whose multiplication is '21' and the same time, whose addition is '10'

So, we get

Hence, First option is correct.

idk

step-by-step explanation:

a is the right answer