what is the quadratic function 3x^2-30x+72 in the form f(x)= a(x-h)^2+k and what is the vertex of it's graph

Answer 1

3(x^2 - 10x) + 72 =

3(x^2 - 10x + 25) + 72 -75 <--- completes the square... 3*25 = 75 is added and subtracted

3(x - 5)^2 - 3

so the vertex is (5,-3)