y=3x²-6x+4
to put in vertex form, make a square by adding (half of b)²
but first, we have to make a=1 by take out the 3:
y=3(x²-2x)+4
b=-2, half of b=-1, (-1)²=1, so add 1, then subtract 1 inside the parenthesis:
y=3(x²-2x+1-1)+4
make the square: y=3[(x-1)²-1]+4
simplify: y=3(x-1)²-3+4=3(x-1)²+1
so the answer is A.
