x2(squared)-12=-x
solve by completing the square
x^2 - 12 = x
Subtract x from both sides.
x^2 - x - 12 = 0
Find two factors of -12 that would add to give the value of -1(x) in the middle term (-4,3) (-3,4)(-6,2)
(-2,6). (If the x^2 term is preceded by a number other than one, you need to find the two factors for that also.)
(x-4)(x+3) = 0
x = 4 or -3