The vertex is relatively easy to find. Find the midpoint of the segment of the x-axis connecting x=2 and x=6; it is x=4. Then evaluate the function at x=4:
f(4) = (4-2)(4-6) = 2(-2) = -4. The vertex is at (4,-4).
Plot (4,-4). Then (arbitrarily) let x=0 and find y: f(0) = y = (-2)(-6) = -12. So, when x = 0, y = -12.
Plot this point (1, -12). realize that the parabola is symmetric about the line x=4. (1,-12) is 3 units to the left of the axis of symm, and thus another point on the parab. is 3 units to the right of this axis, x= 7. Plot (7,-12). Now draw the parabola thru (7,-12), (1, -12) and (4, -4). The parab. opens up.
Division is the usual shortcut for repeated subtraction. You could subtract 5.5 from 264 until you get to zero. You would have to do 48 subtractions. It is easier to divide 264 by 5.5 to see how many times it goes.
