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 <span>x=12 plus or minus the square root of 164 all divided by 2 or in decimal form </span>x = {12.403124237, -0.403124237}