(1)按x的升幂：(y^2-1)-(2y+5)x+x^3; 按x的降幂排列:：x^3-(2y+5)x+(y^2-1)(2)按x的升幂:(2-y^4)-3xy+x^2y^2+x^3; 按x的降幂排列:：x^3+x^2y^2)-3xy+(2-y^4)(3)按x的升幂:(5-6y^2)-5x+3x^2y+x^4; 按x的降幂排列:：x^...