Answer:
f(x) = 3(x -4)^2 +1
Explanation:
Usually you start by factoring the leading coefficient from the first two terms:
f(x) = 3(x^2 -8x) +49
Now, you add the square of half the x-coefficient inside parentheses, and subtract the same quantity outside.
f(x) = 3(x^2 -8x +(-4)^2) -3(-4)^2 +49
= 3(x -4)^2 -48 +49
f(x) = 3(x -4)^2 +1 . . . . . . . . the vertex form you desire