express f(x)= 5(x-9) is standard form Solution Any quadratic function can be written in the standard form f(x) = a(x - h) 2 + k, where h and k are given in terms of coefficients a, b and c. Now we will see how to get the standard form from the general form. Given general form is f(x) = ax 2 + bx + c 5(x-9)=a(x-h)^2+k where ah^2+k=-45 2ah=-5 .