解方程组：{a+2}x+{a+1}y等于a {b+2}x+{b+1}y等于b 注：a不等于b

显示全部楼层 · 2011-6-23 13:50:55

相减(a-b)x+(a-b)y=a-ba-b≠0x+y=1y=1-x所以(a+2)x+(a+1)(1-x)=a(a+2-a-1)x+a+1=a所以x=-1y=1-x=2...

千问 · 2011-6-23 13:50:55

将（a+2)x+(a+1)y=a进行化简得ax+2x+ay+y=a将（b+2)y+(b+1)y=b进行化简得by+2y+by+y=b以上两式相减得（a-b)x+(a-b)y=a-b因为a不等于b，所以x+y=1...

千问 · 2011-6-23 13:50:55

由（a+2)x+(a+1)y=a得ax+2x+ay+y=a由（b+2)y+(b+1)y=b得by+2y+by+y=b以上两式相减得（a-b)x+(a-b)y=a-b因为a不等于b，所以x+y=1...

千问 · 2011-6-23 13:50:55

两式相减：（a+2-(b+2)）x+（a+1-(b-1)）=a-b即：（a-b）x+（a-b）y=a-b∵a≠b∴a-b≠0∴x+y=1∴y=1-x代入式子1，(a+2)x+(a+1)(1-x)=a(a+2-a-1)x+a+1=a∴x=-1,y=2...