Question

Solve x2 + 4x – 12 = 0 by completing the square. Show your work for full credit.

Answer 1

first step add 12 on both sides
\[x^2+4x=12\]
now we want to complete the square on the left hand side so we need to add (b/2)^2
(4/2)^2=2^2=4
we add that on one side we have to do the same to other side
\[x^2+4x+4=12+4\]
\[(x+2)^2=16\]
take square root of both sides
\[x+2=\pm 4\]
now im pretty sure you can subtract 2 on both sides

Answer 2

x^2 + 4x = 12
(x + 2)^2 -4 = 12
(x+2^2 =16
(x+2) = =4 or -4
x = x = 2 or -6