Question

3x^2+7x+2 how to factor​

Answer 1

Work is attached in the image provided.

For your second pair of binomials, (3x + 1)(x + 2), the product of the outer terms is 6x and the product of the inner terms is 1x and 6x + 1x = 7x which is the middle term in you're original trinomial.

So the second pair of binomials represents your answer.

Answer 2

$3 {x}^{2} + 7x + 2 \\ = 3 {x}^{2} + 6x + x + 2 \\ = 3x(x + 2) + 1(x + 2) \\ = (3x + 1)(x + 2)$