what is the solution(s) to the equation 5a^2 - 44 = 81

a) + or - 25
b) -5
c) + or - 5
d) + or - 125

You can find the answer by plugging in any of the multiple choice options into a,
when you square a number (^2), the result is always positive even if the number starts off negative, 
 -25 or 125 wouldn't work for this equation because the answer is too big
but when you plug -5 or 5 in you get the right answer, so the answer is c