已知1<=a+b<=5,-1<=a-b<=3,则3a-2b的取值范围是多少
问题描述:
已知1<=a+b<=5,-1<=a-b<=3,则3a-2b的取值范围是多少
答
3a-2b=1/2(a+b)+5/2(a-b)
1/2 -5/2 -2