Ok so I have to find a quadratic function in standard form for a set of points

Here they are

[-1,2],[0,1],[1,-4]

I plug them into the formula

-2=a[1]^2+b[1]+c

a+b+c

1=a[0]^2+b[0]+c

c=1

-4=a[1]^2+b[1]+c= a+b+c

-2=a+b+1 because c=1

-4=a+b+1

subtract 1

-3=a+b

-5=a+b

Now if I were to make either -3 or -5 positive it would also make the and b negative and it would cross out both the a and b. I can only get rid of one.