What is x value if f(x) = x^2 + 4x - 12

To solve for x , if x^2+4x-12 =
0.

We rewrite  the given equation as : x^2+4x=
12.

We add 2^2 to the left side in or der that the left
side is a perfect square:

x^2+4x+2^2 =
12+2^2

(x+2)^2 = 16.

We take
square root of both sodes to solve for x:

x+2 = sqrt16 . Or
x+2 = -sqrt16.

x+2 = 4  gives x = 4-2 =
2.

x+2 = -4 gives: x= -4-2 =
-6.

Therefore x= 2 or x= -6 are solutions
.

Tally:

We put  x= 2 in
x^2+4x-12 : 2^2+4*2-12 = 4+8-12 = 12-12 = 0 = RHS.

We put
x= -6 in x^2+4x-12 : (-6)^2+4(-6) -12 = 36-24 -12 = 12-12 = 0 =
RHS.