Question

Solve the equation by completing the square.

X^2 – 12x = 13

First we add (-12/2)^2 to both sides to get

x^2 - 12x + 36 = 49.

Then square root each side and solve.

A. {46, 55}

B. {-15, 27}

C. {-1, 13}

D. {-21, 33}

Answer 1

C

Explanation:

x² - 12x + 36 = 49

(x - 6)² = 49

now taking the square root

x - 6 = 7

x = 13

the second solution is (remember, sqrt(a²) = ±a)

-(x - 6) = 7

-x + 6 = 7

-x = 1

x = -1