Question

Complete the square to solve for x.

x^2+4x−21=0

Answer 1

Well, do it!

(x^2 + 4x + ______) - 21 - _______ = 0

The blanks are the same.

Answer 2

x^2+4x=21

x^2+4x+___=21+___

x^2+4x+4=21+4

(x+2)^2=25

x+2=+ or - sqrt25

x=-2 + sqrt 25 or x = -2 - sqrt 25

x=-2+5 or x -2-5

x=3 or x = -7

Answer 3

thank you, i got the same thing!