｛ax+2y=2,x-y=-36有无穷组解时,方程2ax+5=6b的解是_______
问题描述：
｛ax+2y=2,x-y=-36有无穷组解时,方程2ax+5=6b的解是_______
写错了，应是｛ax+2y=2,x-y=-3b
答
ax+2y=2.(1)
x-y=-3b.(2)
(1)+(2)*2得
(a+2)x=2-6b
有无穷组解
故
a+2=0
2-6b=0
得
a=-2
6b=2
2ax+5=6b
-4x+5=2
4x=3
x=0.75