3x/4 +2y=-x/3 -5y=3x/7+y-2由3x/4 +2y=-x/3 -5y,移项(3/4 +1/3)x=(-5-2)y,-->(13/12)x=-7y,由3x/4 +2y=3x/7+y-2,移项(3/4 -3/7)x=y-2-2y,-->(9/28)x=-y-2,两方程相除,91/27=7y/(y+2),y=13/7,代入第一个方程,(13/12)...