Question

Solve x2 + 4x – 12 = 0 by completing the square.
Please help!

Answer 1

\[x^2+4x=12\]
added 12 on both sides

Answer 2

\[x^2+4x+4=12+4\]
added 4 on both sides to complete the square on the left hand side

Answer 3

\[(x+2)^2=16\]

Answer 4

Now take square root of both sides
don't forget the plus or minus

Answer 5

\[x+2 = \pm \sqrt{16}\]
\[x+2= \pm 4\]

Answer 6

Now subtract 2 on both sides
\[x=-2 \pm 4\]
this means we have two values for x
\[x=-2+4 \text{ or } x=-2-4\]

Answer 7

\[x=2 \text{ or } x=-6\]

Answer 8

\[x ^{2}+4x+4-16=0 \rightarrow (x+2)^2=16 \rightarrow x+2= \pm 4;\]; x=2 and x=-6

Answer 9

x2 + 4x – 12 = 0
x^2+6x-2x-12 =0
x(x+6)-2(x+6) = 0
(x+6)(x-2) = 0
x = -6,2

Answer 10

thanks guys! (: