方程组{x+y+z=50,1500x+2100y+2500z

问题描述:

方程组{x+y+z=50,1500x+2100y+2500z
方程组是{x+y+z=50,1500x+2100y+2500z=90000

X=50-y-z再把x=50-y-z代入1500x+2100y+2500z