(1)①-1+y²-5x-2xy+x³
②y²-2xy+x³-5x-1
(2)①2-y^4-3xy+x²y²+x³
②-y^4+x²y²-3xy+x³+2
(3)①5-6y²-5x+3x²y+x^4
②-6y²+3x²y+x^4-5x+5