Answer:
3(x + 12)(x + 2)
Step-by-step explanation:
Given
3x² + 42x + 72 ← factor out 3 from each term
= 3(x² + 14x + 24) ← factor the quadratic
Consider the factors of the constant term (+ 24) which sum to give the coefficient of the x- term.
The factors are + 12 and + 2, since
12 × 2 = 24 and 12 + 2 = 14, thus
x² + 14x + 24 = (x + 12)(x + 2) and
3x² + 42x + 72
= 3(x + 12)(x + 2) ← in factored form
