program - finding the roots of the quadratic equation in subset of real numbers

Hi all,

i want to write a program in MathCad 15, that can find a roots of the quadratic equation in subset of real numbers. Result will be a vector, or text: "this equation dont have result in real numbers"

I already have a program, that can find a roots:

but i dont know how to continue..

i think, that if b^2-4*a*c <0 than this  equation dont have results in real numbers. but how can i write this in program?

Thanks a lot!