$$ax^2 + bx + c = 0$$ is a quadratic equation, $$a$$, $$b$$, $$c$$ are rational numbers. $$\Delta = b^2 - 4ac$$.

A

Roots of the equation are always real

B

If $$\Delta = k^2$$, $$k$$ is rational, then roots are rational

C

If $$\Delta \ne k^2$$, $$k$$ rational, then the roots are rational conjugates

D

Roots of the equation are always rational