N是M的子集,则M包含Na+1>-22a-1<5则-3同时,当a=-3,或者a=2时也成立则-3<=a<=2
若N是M的子集则有-2<=a+1<=x<=2a-1<=5所以 -2<=a+1 2a-1<=5解不等式组得-3<=a<=2