Question

How do you find the missing number or term to make a perfect square trinomial. `y^2 + 5y + ___`?

Answer 1

`(y+k)^2 = y^2+2ky+k^2`

So if we let `k=5/2`, we find...

`(y+5/2)^2 = y^2+5y+25/4`

In the most general case:

`ay^2+by+c = a(y+b/(2a))^2 + (c-b^2/(4a))`