Question

Find the exact solution of the following quadratic equation by using the Quadratic Formula. x^2-9x=36

Answer 1

Answer:

x = 12 or x = -3

Step-by-step explanation:

Solve for x over the real numbers:

x^2 - 9 x = 36

Subtract 36 from both sides:

x^2 - 9 x - 36 = 0

x = (9 ± sqrt((-9)^2 - 4 (-36)))/2 = (9 ± sqrt(81 + 144))/2 = (9 ± sqrt(225))/2:

x = (9 + sqrt(225))/2 or x = (9 - sqrt(225))/2

sqrt(225) = sqrt(9×25) = sqrt(3^2×5^2) = 3×5 = 15:

x = (9 + 15)/2 or x = (9 - 15)/2

(9 + 15)/2 = 24/2 = 12:

x = 12 or x = (9 - 15)/2

(9 - 15)/2 = -6/2 = -3:

Answer:  x = 12 or x = -3