化简(4x²-5xy)-(1/3y²+2x²)+2(3xy-1/4y²-1/12
已知x²-xy=4,y²-xy=9求下面代数式的值(1)x²-2xy+y²;(2
已知x=3 y=1\3,求3x²y-[2xy²-2﹙xy-3\2x²y﹚+xy]+3xy&
3x²y+xy²-[2xy²-4x²y+(x²y-2xy²)
2xy-1/2(4xy-8x²y²)+2(3xy-5x²y²),其中x=3/2,
2x²-5x+x²+4x-3x² -3x²y+2xy²+3xy
(3x+2y)(9x²-6xy+4y²﹚
3x²y-﹛xy-[3xy-(4xy²+½xy)]-4x²y﹜
先化简再求值xy﹙x²+y﹚-y²﹙xy+2x﹚-3xy²,其中x=5,y=﹣1
计算 2xy[4x²y²-3y(xy+x²y)-xy²]
化简求值:4xy-(2x²+5xy-y²)+2(x²+3xy),其中x=负2,y=二分之一
去括号:1/2(2X²Y-3XY²+4XY-X²Y²)=?
(-2/3X³y+4x²y²-1/2xy²)/(-xy/4) 急