通分①x／3y与3x／2y²②x-y／2x+2y与(x-y)／(x+y)²③2mn／4m²-9与2m／2m+3

通分①x／3y与3x／2y²②x-y／2x+2y与(x-y)／(x+y)²③2mn／4m²-9与2m／2m+3
通分①x／3y与3x／2y²②x-y／2x+2y与(x-y)／(x+y)²③2mn／4m²-9与2m／2m+3

通分①x／3y与3x／2y²②x-y／2x+2y与(x-y)／(x+y)²③2mn／4m²-9与2m／2m+3
①x／(3y)=2xy/(6y²)
3x／(2y²)=9x/(6y²)
②(x-y)／(2x+2y)=(x²-y²)/[2(x+y)²]
(x-y)／(x+y)²=2(x-y)/[2(x+y)²]
③2mn／(4m²-9)
2m／(2m+3)=2m(2m-3)/(4m²-9)