Answer:
(x + 3)(3x - 4)
Explanation:
Given
3x² + 5x - 12
Consider the factors of the product of the coefficient of the x² term and the constant term which sum to give the coefficient of the x- term.
product = 3 × - 12 = - 36 and sum = + 5
The factors are + 9 and - 4
Use these factors to split the x- term
3x² + 9x - 4x - 12 ( factor first/second and third/fourth terms )
= 3x(x + 3) - 4(x + 3) ← factor out (x + 3) from each term
= (x + 3)(3x - 4)
Thus
3x² + 5x - 12 = (x + 3)(3x - 4) ← in factored form