We have these equations
-11 = (-1)^2 + b(-1) + c
-17 = (3)^2 + b(3) + c simplify
-11 = 1 -b + c
-17= 9 + 3b + c
-12 = -b + c
-26 = 3b + c subtract these
14 = -4b
14/ -4 = b = -7/2
And we can find c as
-12 = - (-7/2) + c
-12 = 7/2 + c
-12 - 7/2 = c = -24/2 - 7/2 = -31/2
+1348 
