Question

解方程组:{x-y-z=-1,3x+5y+7z=11,4x-y+2z=-1

Answer 1

答案：x=1,y=3,z=-1

由一式得x=y+z-1,设为四式

将四式代入二式和三式,得{3(y+z-1)+5y+7z=11,4(y+z-1)-y+2z=-1

即{8y+10z=14,3y+6z=3

由此可解出z=-1

将z=-1代入8y+10z=14,得y=3,再将y=3代入x=y+z-1,得出x=1