Ответы
1)
18 ≤ 6х ≤54,
6х ≤ 54, 6х ≥ 18,
х ≤9, х ≥ 3,
-------*-------------*----------⇒
3 9
х ∈ [3; 9],
2)
-7 < х - 5 < 13,
х - 5 > -7, х - 5 < 13,
x > -7 + 5, x < 13 + 5,
x > -2, x < 18,
-------*-------------*----------⇒
-2 18
x ∈ (-2; 18),
3)
-33 < 7 + 2x ≤ 25,
7 + 2x > -33, 7 + 2x ≤ 25,
2x > -33 - 7, 2x ≤ 25 - 7,
2x > -40, 2x ≤ 18,
x > -20, x ≤ 9,
-------*-------------*----------⇒
-20 9
x ∈ (-20; 9],
4)
-12 ≤ 6 - 3/7x < 36,
6 - 3/7x ≥ -12, 6 - 3/7x < 36,
-3/7x ≥ -12 - 6, -3/7x < 36 - 6,
-3/7x ≥ -18, -3/7x < 30,
-x ≥ -42, -x < 70,
x ≤ 42, x > -70,
-------*-------------*----------⇒
-70 42
x ∈ (-70; 42]
1)
Ответ: [3;9]
2)
Ответ:(-2;18)
3)
Ответ: (-20; 9]
4)
Ответ:( -70; 42 ]