Find the exact solutions of the systems of equation x^2+2y^2=18 and x=2y

Answer 1

(2y)^2 + 2 y^2 = 18
4 y^2 + 2 y^2 = 18
6 y^2 = 18
y^2 = 3
y = +sqrt 3 or -sqrt 3
x^2 + 2 *3 = 18
x^2 = 12
x = + or - 2 sqrt 3

Answer 2

20=+or-2 sqrt 3=5