已知方程组x＋2y＝3m x-y＝9m,得解满足5x＋8y＝38,求m的值
问题描述：
已知方程组x＋2y＝3m x-y＝9m,得解满足5x＋8y＝38,求m的值
答
根据x-y=9m,得x=9m+y,带入x+2y=3m,得9m+y+2y=3m,得出y=-2m
将y=-2m带入x=9m+y,得到x=7m,
将x=7m,y=-2m带入5x+8y=38,
得35m-16m=38,
19m=38,得出m=2