Question

Solve x2 − 10x = −21. (6 points)

Answer 1

x = -7 and x = -3

Explanation:

You can solve this by completing the square

x^2 - 10x + _ = -21 + _

(b/2)^2

(10/2)^2

(5)^2 = 25

x^2 - 10x + 25 = -21 + 25

(x + 5)^2 = 4

now square root the left side and the right

x + 5 = +/- 2

subtract 5 from both sides

x = -5 +/- 2

-5 + -2

-5 - (-2)

x = -7 and x = -3 :)