Q:

The intersections of two equations

I have these two functions, that I must solve.

When I plot them, I see there are 4 intersections:
$$(1,0),(0,1),(-1,0),(0,-1)$$
But how do you solve these??

A:

$g(x,y)=(x+y+1)(x+y-1)=(x+y)^2-1=x^2+y^2-1=f(x,y)\Rightarrow xy=0$, so their intersections are $x=0$ or $y=0$. (Your answer is just part of them.)

