Find all real solutions to 100x^2 + 20x + 1 = x^2 + 8x + 16.
100x^2 + 20x + 1 = x^2 + 8x + 16. Gather everything to the left side
99x^2 + 12x -15 = 0 Now you can use the Quadratic Formula to find x = 66/198 and - 90/198 (simplify if needed)
\(x = {-b \pm \sqrt{b^2-4ac} \over 2a}\) a = 99 b = 12 c = -15
Picking up on EP's solution without the Q Formula
99x^2 + 12x - 15 = 0 divide through by 3
33x^2 + 4x - 5 = 0 factor as
(11x + 5) ( 3x -1 ) = 0
Set each factor to 0 and solve for x
11x + 5 = 0 3x - 1 = 0
11x = - 5 3x = 1
x = - 5 /11 x = 1/3