3m的平方-【5m-(2分之1m-3)+2m的平方】+4
问题描述：
3m的平方-【5m-(2分之1m-3)+2m的平方】+4
答
解
3m²-[5m-(1/2m-3)+2m²]+4
=3m²-(5m-1/2m+3+2m²)+4
=(3m²-2m²)-9/2m+(4-3)
=m²-9/2m+1