In a step of the derivation of the quadratic formula, we have plus or minus sqrt(b^2-4ac/(4a^2)) = plus or minus sqrt(b^2 - 4ac)/2a. Basically just took the square root of the bottom of the fraction. My question is, doesnt the a in the denominator of the last expression have to be |a| because we took the square root of a ^2 ? If this is not the case, why not?