5mn-（5mn+（2m的2次方n+（m的2次方n-3mn））-2m的2次方n）要求写原式=去括号=结果=结果
问题描述：
5mn-（5mn+（2m的2次方n+（m的2次方n-3mn））-2m的2次方n）
要求写原式=去括号=结果=结果
答
5mn-（5mn+（2m的2次方n+（m的2次方n-3mn））-2m的2次方n）
=5mn-{5mn+[2m²n+（m²n-3mn）]-2m²n}
=5mn-[5mn+(2m²n+m²n-3mn)-2m²n]
=5mn-(5mn+3m²n-3mn-2m²n)
=5mn-5mn+m²n-3mn
=m²n-3mn
=mn(m-3)
答
5mn-{5mn+[2m的2次方n+（m的2次方n-3mn）]-2m的2次方n}
=5mn-{5mn+[2m^2n+m^2n-3mn]-2m^2n}
=5mn-{5mn+[3m^2n-3mn]-2m^2n}
=5mn-{5mn+3m^2n-3mn-2m^2n}
=5mn-{2mn+m^2n}
=5mn-2mn-m^2n
=3mn-m^2n