The question asks

Find the range of values of k that give this equation two distinct real roots. 3x^2 +kx +2=0.

I have used the determinant and get the answer k >+/- 2X6^1/2. The answer book says k< -2X6^1/2 and k>2X6^1/2. Can someone explain why this is. I am trying to teach myself A level maths (1st year)