Plug the values into the equation and you will have four linear equationsOriginally Posted byfreswood

in a, b, c and d. These can then be solved by the usual methods ( lets

say Gaussian elimination for example.)

For instance:

The first point (0,1) corresponds to x=0, y=1, so:

1=d;

the second point (1,3) corresponds to x=1, y=3, so:

3=a+b+c+d;

the third point (-1,-1) corresponds to x=-1, y=-1, so:

-1=-a+b-c+d;

the fourth point (2,11) corresponds to x=2, y=11, so:

11=8a+4b+2c+d.

RonL