For what real values of a is x^2 + ax + 125 the square of a binomial? If you find more than one, then list the values separated by commas.
(x - sqrt 125) ( x - sqrt 125) = x^2 - 2sqrt (125)x + 125
( x + sqrt 125) ( x + sqrt 125) = x^2 + 2sqrt (125)x + 125
a = -2 sqrt (125) and 2 sqrt (125)
Simplified
a = -10sqrt 5 and 10sqrt 5
