Consider the general quadratic function f(x)=ax2+bx+c with a>0. By calculating the minimum value of this function, show that f(x)[tex]\geq[/tex]0 for all x if and only if b2-4ac[tex]\leq[/tex]0
The Attempt at a Solution
I know that the min for a quadratic equation is at x=-b/2a and I proved this by taking the derivative of f(x) and setting it equal to zero. I then plugged this in for x to get c+ax2 but I don't know where to go from there.