越快越好(1)(xy²+3)(xy²+3)-2x(-x+y)(2)(x+2)(x²+4)(x-2)(3)先化简,再求值(x²y²-4)(-x²y²-4)-4(xy-1/2)(xy-1/2)其中x=1,y=-2(4)(-x-2y)(x-2y)半小时内解决,

问题描述:

越快越好
(1)(xy²+3)(xy²+3)-2x(-x+y)
(2)(x+2)(x²+4)(x-2)
(3)先化简,再求值(x²y²-4)(-x²y²-4)-4(xy-1/2)(xy-1/2)其中x=1,y=-2
(4)(-x-2y)(x-2y)
半小时内解决,

1 x^2y^4+2x^2+6xy^-2xy+9
2 x^4-16
3 -x^4y^4-4x^2y^2+4xy+15 值-25
4 4y^2-x^2