-22=a-b+c (1)
-8=c (2)
8=4a+2b+c (3)
(1)x2
-44=2a-2b+2c (4)
(3)+(4)
-36=6a+3c
-36=6a-24
a=-2
-22=a-b+c
-22=-2-b-8
b=12
y=-2x^2+12x-8