for a quadratic "expression"
i.e. ax^2 + bx + c
with any real and integral value of a, b and c
how to show that if delta (b square minus 4ac) is a perfect square
then such a quadratic expression can be factorized by cross method?
into something like (mx-n)(px-q) where m,n,p,q are integers.
I had been thinking about it for a whole night.
Hope someone can help