make equal to zero
x^2-4x=2x+24
minus 2x both sides
x^2-4x-2x=24
minus 24
x^2-6x-24=0
comlpete the square
isolate x^2 and x term
(x^2-6x)-24=0
take 1/2 of -6 and square it (-6/2=-3 (-3)^2=9) and add to both sides inside parethaes
(x^2-6x+9)-24=9
factor perfect square
(x-3)^2-24=9
add 24 both sides
(x-3)^2=33
sqrt both sides
x-3=+/-√33
add 3 to both sides
x=3+/-√33
x=3+√33 or 3-√33