Math Help - how do you find the intersection of

1. how do you find the intersection of

so how do you find the intersection of

$x^2+y^2=18$

and

$y=x$

algebraically?

2. Originally Posted by behindDkeys
so how do you find the intersection of

$x^2+y^2=18$

and

$y=x$

algebraically?
Substitute $y=x$ into $x^2+y^2=18$

Solve for x

3. Originally Posted by running-gag
Substitute $y=x$ into $x^2+y^2=18$

Solve for x

but then i'll get like positive and negative 9

do i substitute the value of x to each equation and right down what i got?

then i'll get 4 solutions o.o

is that right?

4. No