Question

What must be added to
4x2+20x+16 so that it becomes a perfect square​

Answer 1

Answer:

4x2+20x+16

(2x)^2+2.(2x).5+5^2+16-5^2

(2x+5)^2-9 {As (a+b)^2=a^2+2.a.b+b^2}

Therefore 9 to be added to the above equation to become a perfect square.

And;9