For which equation does it make the most sense to solve by completing the square? 5x² + 3x = 9 3x2−x+17=0 x² + 20x = 52 x2−8=1

x² + 20x = 52.  Why?  Completing the square is easier for this equation in comparison to completing the square for the first two equations.

x^2-8=1 becomes x^2=9, so that x=plus or minus 3.  Why bother with completing the square here?

x^2 + 20x                          = 52
x^2 + 20x + 100 - 100       = 52
       (x+10)^2                    = 152

taking the sqrt of both sides:

x+10 = plus or minus sqrt(152)    (and so on).

The answer is