Question

To answer this I would just sub in the x and y values right? I got a) as my answer since it equals 0.

Which of the following would describe the sketch of the expression xy+2y-3x-6=0
a) the planes x=-2 and y=3
b) the planes x=3 and y=-2
c) the planes x=6 and y=2
d) the planes x=3 and y=6

Answer 1

Actually, the expression is the expanded form of
(x+2)(y-3)=0
which by the zero-product property means
x+2=0 => x=-2, or
y-3=0 => y=3, or
both of the above.
So yes, (a) is correct.