Answer:
Let x be the number
double x = 2 x
square the result (2x)^2
(2x)^2 - x subtract the original number
4 x^2 - x = 33
4 x^2 - x - 33 = 0
Solve the quadratic
(1 +- (1 + 4 * 132)^1/2) / 8
= (1 + 528^1/2) / 8 = (1 + 23) / 8 = 3 using the positive exponent
Check:
(2 * 3)^2 - 3 = 36 - 3 = 33
