Find an equation for the plane that is perpendicular to v = (1, 1, 1) and passes through (1, 0, 0).

The perpendicular vector delivers you the coefficients of the x,y,z variables, so you know that your plane will have the equaction x+y+z = c.

Now all you have to do is find c to make the plane pass through (1,0,0).

If you fill in this point, you get c=1, so the equation is:

x+y+z=1.

2xy/9 is the answer to this problem