Question

已知a+b大于等于1,小于等于5,a-b大于等于-1,小于等于3,求3a-2b的取值范围

Answer 1

3a-2b=1/2(a+b)+5/2(a-b)

1/2 < 1/2(a+b) < 5/2

-5/2 < 5/2(a-b) < 15/2

-2< 3a-2