1) 2x/x²-y + 5x-2y/y²-x²

2) a²b/ab-2 + ab²/ab-2 + 2a+2b/2-ab

X²-xy-2y²=0 x²+y²=20 x²-xy-2y²=0 x²+xy-2xy-2y²=0 x (x+y) - 2y (x+y) = 0 (x-2y) (x+y) = 0 x+y=0 x²+y²=20 x=-y x²+y²=20 (-y) ²+y²=20 y²+y²=20 2y²=20 y²=10 y=-√10 ∨ y=√10 x=√10 ∨ x=-√10 x-2y=0 x²+y²=20 x=2y x²+y²=20 (2y) ²+y²=20 4y²+y²=20 5y²=20 y²=4 y=-2 ∨ y=2 x=2 * (-2) ∨ x=2*2 x=-4 ∨ x=4