x^2-kx+9 = 0 then when the roots are real? k>6, k<6 k = 6 or none?
I plugged in the numbers for K. But the answer did not look right. I could be wrong though, I might have did it the wrong way.
With the usual notation, for real roots you need b^2 - 4ac >= 0.
Plug in the values for a and c, and (-k) for b and see what that tells you about k.