Step-by-step explanation:
the solution are
x = 1 or x = -15
x^2 + 14x - 15 =0
x^2 + 14x = 15
to write the left hand side as a perfect square we add 49 to both sides :
x^2 + 14x + 49 = 15 + 49
x^2 + 2.x.7 + 7^2 = 64
using the identity (a^2 + b^2) = a^2 + 2ab + b^2
(x + 7)^2 = 64
x + 7 = √64 or x + 7 = -√64
x = 8 - 7 or x = - 8 - 7
= 1 = - 15
