成都赵师兄
幼苗
共回答了30个问题采纳率:86.7% 举报
1 n为41或42
2、x+y=1000,0.06x-0.02y=1000*0.044x=800y=200
3、由题可知:4x-3y=6z x+2y=7z 下式乘4减上式得: (x+2y)*4-(4x-3y)=7z*4-6z 化简 得:y=2z 将y=2z代入x+2y=7z ,得x+4z=7z,解得x=3z 将y=2z x=3z代入(2x+3y+6z)/(x+5y+7z),得 (6z+6z+6z)/(3z+10z+7z)=18z/20z=0.9
1年前
1