Question

What number should be added to the expression x2 + 12x to change it into a perfect square trinomial? (a.6 ( b.18 (c.12 (d.36

Answer 1

Hello : 
x²+12x =x²+2(6)(x)
            = x²+2(6)(x) +6²-6²
            = (x-6)² -6²........ (answer : d ; 36)