Question

What must be subtracted from 4x^2+12x+4 to make it a perfect square?

Answer 1

4x^2+12x+4= (2x)^2+(2.2x.3)+4 =. (2x)^2+(2.2x.3)+4+5-5 =(2x)^2+(2.2x.3)+3^2-5 =(2x+3)^2-5 . So, 5 should be subtracted.