Simultaneous Linear and Quadratic Equations

Now I know the rules about this one, But I can't work out the second half of the sum,

**1st half:**

*1. Find the value of such that the line with equation is a tangent to the parabola with equation *

the determinant = 0 then there is only one intersection (tangent)

through DOPS

therefore

**Now this is the part, I don't understand,**

2. Find the possible values of c such that the line with equation ** *** twice intersects the parabola with equation *

Any help would be much appreciated,

Thanks,

22upon7