Solve for x: x^2+4x-5=16x

Solve for x: x^2+4x-5=16x
first take 16x from both sides of the equation
x²-12x-5=0
now we have a quadratic. we can solve it by using the quadratic formula
x=-b plus or minus the square root of b²-4ac all divided by 2a
where a=1, b=-12 and c=-5
plug these numbers into the formula
x=12 plus or minus the square root of 144-4x1x-5 all divided by 2
x=12 plus or minus the square root of 164 all divided by 2
or in decimal form x = {12.403124237, -0.403124237}