The quadratic 3x^2-24x+72 can be written in the form a(x+b)^2+c, where a, b, and c are constants. What is a+b+c?
3x^2-24x+72
3 ( x^2 -8x) + 72
3 (x-4)^2 + 72 -48
3 (x-4)^2 + 24 <====== you can finish