Completing the Square is required to solve this equation. First, identify A,B, and C of the quadratic equation: A=1, B=8, C=15. Halve B to obtain a: B/2 = 8/2 = 4 so a = 4. Substitute a into the form (x+a)2-b: (x+4)2-b. Square a because it is within the squared brackets: a2 = 42 =16. Subtract the square of a from the equation (x+4)2-b: (x+4)2-16. Add C to the equation to obtain the final answer: (x+4)2-16 +15 = (x+4)2-1. ANS=(x+4)2-1