Hello,
Prove that the roots of the following equation is rational:
$\displaystyle abc^2x^2 +3a^2cx+b^2cx-6a^2-ab+2b^2 $
Thanks
I think your question is incomplete. I am guessing that a,b and c should be rational numbers. The expression given is a quadratic. You should know a formula for the roots of a quadratic. Plug it into the formula and use what you know about fractions, differences and sums of rational numbers and you will have your proof.