Решите двойное неравенство:
а) -9 < 3х < 18;       в) 3 ≤ 5х - 1 ≤ 4;
б) 1 < (2x-1)/2 < 2; г) 0 ≤ (1-x)/3 ≤ 1.

Решение:


а) -9 < 3х < 18 => -3 < x < 6
б) 1 < (2x-1)/2 < 2 => 2 < 2x - 1 < 4 => 3 < 2x < 5 => 1,5 < x < 2,5;
в) 3 ≤ 5х - 1 ≤ 4 => 4 ≤ 5x ≤ 5 => 0,8 ≤ x ≤ 1;
г) 0 ≤ (1-x)/3 ≤ 1 => 0 ≤ 1 - x ≤ 3 => -1 ≤ -x ≤ 2 => -2 ≤ x ≤ 1.