满足2x-3y=11-4m和3x+2y=21+5m的x,y,也满足x+3y=10+7m求m
问题描述:
满足2x-3y=11-4m和3x+2y=21+5m的x,y,也满足x+3y=10+7m求m
答
x+3y=10+7m 和2x-3y=11-4m相加得到x=7+m代入3x+2y=21+5m得到21+3m+2y=21+5m所以y=m
代入最后一个:7+m+3m=10+7m.所以m=-1
x=6,y=-1
答
M=-1/6
答
2x-3y=11-4m①
3x+2y=21+5m②
x+3y=10+7m③
①+③,得3x=21+3m,x=7+m
①*2+②*3,得13x=22-8m+63+15m,13x=85+7m
13(7+m)=85+7m
91+13m=85+7m
5m=-6
m=-6/5