Answer:
B
Step-by-step explanation:
Given
3x² + 21x + 18 ← factor out 3 from each term
= 3(x² + 7x + 6) ← factor the quadratic
Consider the factors of the constant term (+ 6) which sum to give the coefficient of the x- term (+ 7)
The factors are + 6 and + 1, since
6 × 1 = 6 and 6 + 1 = 7, thus
x² + 7x + 6 = (x + 6)(x + 1)
Thus
3x² + 21x + 18 = 3(x + 6)(x + 1) → B
