Complete the square x squared + 18x-64=0

x = - 9±√145 ( = 3.04 or - 21.04)

Step-by-step explanation:

x²+18x-64 = 0 (move the constant to the right side, add 64 to both sides)

x²+18x = 64 (divide the x-term by 2, square it, then add it to both sides)

x²+18x + (18/2) ² = 64 + (18/2) ² (simplify)

x²+18x + 9² = 64 + 9²

x²+18x + 9² = 64 + 81

x²+18x + 9² = 145 (simplify left side using the property (a+b) ² = a² + 2ab+b²)

(x+9) ² = 145 (take square root of both sides)

x+9 = ±√145

x = - 9±√145 ( = 3.04 or - 21.04)