Question

solving quadratic equation x2+8x=-15,find third term but answer should be 16

Answer 1

x^2 + 8x + 15 = 0
=> x^2 + 5x + 3x + 15 = 0
=> x(x+5) + 3(x+5) = 0
=> (x+3)(x+5) = 0

Hope it helps.