Don't look at the discriminant for k2 + 6k + 5 = 0 .2
b^2 - 4ac
Look again at what
k2 + 6k + 5 is the discriminant for the original quadratic equation....
You want values of k for which the discriminant is non-negative. You have identified values of k for which the discriminant is zero.
Edit: To be clear, you are on the right track and doing well now.
Edit: And reading back to the original problem statement we want values of k for which the discriminant is negative.
Solve the inequality: k2 + 6k + 5 < 0 .