2分之M+3分之N=2,0.2M+0.2N=2.8怎么解
问题描述:
2分之M+3分之N=2,0.2M+0.2N=2.8怎么解
除了上面的题以外,3分之X,5分之Y=1.3(X+Y)+2(X-3Y)=15,已知|X+2Y-1|+(X-Y+2)2次方=0,求2X+2Y=7的值.50分,10点以前.
答
(m/2+n/3=2)*3得3m+2n=12.①
(0.2m+0.2n=2.8)/0.2得m+n=14.(m+n=14)*3得3m+3n=42.②
②-①得n=30,代入①,得m=-16
后一题麻烦写清楚点,看不懂