来自杜根远的问题
先化简在求值;(-1/3XY)²×[xy(2x-y)-2x(xy-y)²],其中X=-2/3,Y=2我算的是-7
先化简在求值;(-1/3XY)²×[xy(2x-y)-2x(xy-y)²],其中X=-2/3,Y=2
我算的是-7
3回答
2020-09-30 08:31
先化简在求值;(-1/3XY)²×[xy(2x-y)-2x(xy-y)²],其中X=-2/3,Y=2我算的是-7
先化简在求值;(-1/3XY)²×[xy(2x-y)-2x(xy-y)²],其中X=-2/3,Y=2
我算的是-7
(-1/3xy)²×[xy(2x-y)-2x(xy-y)²]=1/9x²y²×[2x²y-xy²-2x(x²y²-2xy²+y²)]=1/9x²y²×[2x²y-xy²-2x³y²+4x²y²-2xy²]...
第二步算错了应该是(-1/3xy)²×[xy(2x-y)-2x(xy-y)²]=1/9x²y²×[2xy-xy-2x(x²y²-y²)]
不对,是:(-1/3xy)²×[xy(2x-y)-2x(xy-y)²]=1/9x²y²×[2x²y-xy²-2x(x²y²-2xy²+y²)]