Answer
$(-1, -3)$, $(-1,3)$, $(1,-3)$, $(1,3)$
Work Step by Step
$x^2+y^2=10$
$9x^2+y^2=18$
$9x^2+y^2-(x^2+y^2)=18-10$
$9x^2+y^2-x^2-y^2=8$
$8x^2=8$
$8x^2/8=8/8$
$x^2=1$
$\sqrt {x^2}=\sqrt 1$
$x=±1$
$x^2+y^2=10$
$1+y^2=10$
$1+y^2-1=10-1$
$y^2=9$
$\sqrt {y^2} =\sqrt 9$
$y = ±3$
