方程组ax-by=6 2x+3y=7与方程组4x-5y=3 ax+by=2的解相同,则2x+3y=7.(1)4x-5y=3.(2)(1)*2-(2),得11y=11y=1代入(1)2x+3*1=72x=4x=2把x=2,y=1代入ax-by=6,ax+by=2中,得2a-b=6.(3)2a+b=2.(4)(3)+(4),得4a=8a=2代入(3)2*2...