Find a formula for the following functions:
x -2 -1 0 1 2 3 4
y 0 3 4 3 0 -5 -12
x -4 -3 -2 -1 0 1 2 3 4
y 25 16 9 4 1 0 1 4 9
The first one looks like an inverted parabola of the form
y = 4 - ax^2
See what value of a works.
The second one looks like a upward-facing parabola with a minimum at (x=1, y=0)
Try y = b(x-1)^2
and see what value of b works.