2x-3y=5 1式3x-2y=7 2式1式*3 2式*26x-9y=15 3式6x-4y=14 4式4式-3式得 5y=-1 y=-1/5代入2x-3y=5x=11/5 x=11/5y=-1/5
2x—3y=5把它变换形式。2* (2x—3y l=5*2
2x=5+3y ; x=5+3y/23[(5+3y)/2]-2y=7(15+9y)/2-2y=715/2+9y/2-4y/2=75y/2=7-15/2y=3x=7