3(5x + 2) > x - (3x - 23)
15x + 6 > x - 3x + 23
15x + 6 > -2x + 23
15x + 2x > 23 - 6
17x > 17
x > 1.
4(x + 8) - 7(x - 1) = 12
4x + 32 - 7x + 7 = 12
-3x = 12 - 32 - 7
-3x = -27
x = 9.
3x² - 27 = 0
3(x² - 9) = 0
(x - 3)(x + 3) = 0
x = -3; 3.
5x² - 4 = 0
(x√5 - 2)(x√5 + 2) = 0
x = -2/√5; 2/√5.
x² - 1 < 0
(x - 1)(x + 1) < 0
+ -1|||||||||-||||||||||||1 +
------------0-------------------0-----------> x
x ∈ (-1; 1).