解方程组:{x-y-z=-1,3x+5y+7z=11,4x-y+2z=-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