any quadratic function can be represeted by the form y=ax²+bx+c where a, b, and c are all constants sometimes we use f(x) instead of y
anyway
we can find the values of a, b, and c by subsituting the points
ok for (-2,-20) x=-2 and y=-20 -20=a(-2)²+b(-2)+c or -20=4a-2b+c
for (0,-4) x=0 and y=-4 -4=a(0)²+b(0)+c -4=c neato we can subsitute -4 for c later to find a and b later
using (4,-20) x=4 and y=-20 (at this point we notice that (-2,-20) and (4,-20) have same y values so the x value of the vertex will be the midpoint of the 2 x values which is at x=1 and we can do math to find the other things but whatever) x=4 and y=-20 -20=a(4)²+b(4)+c -20=16a+4b+c