Answer:
Step-by-step explanation:
3x^2+kx+12=0
k= -3x-12/x
k = 12
3(x² + kx + 2²) = 3(x² + ____x + 4) = 3(x² + 4x + 4) = 3x² + 12x + 12 ⇒ k = 12
