初二下册数学题三道~1.化简:2x²y/3mn²·5m²n/4xy²÷5xym/3n2.化简:x²/y·y/x÷（-y/x）3.化简：（xy-x²）·xy/x-y要过程!!!!

Question

初二下册数学题三道~
1.化简:2x²y/3mn²·5m²n/4xy²÷5xym/3n
2.化简:x²/y·y/x÷（-y/x）
3.化简：（xy-x²）·xy/x-y
要过程!!!!

Answer 1

1.化简:2x²y/3mn²· 5m²n/4xy² ÷5xym/3n=（2x²y*5m²n*3n）/（3mn²· 4xy² *5xym）【为了简算,把所有的分子、分母分开,不易出错】=1/(2y²)2.化简:x²/y·y/x÷（-...