Mark M. answered 02/19/21
Retired math prof. Calc 1, 2 and AP Calculus tutoring experience.
l 2x - 3 l < 7 means that 2x - 3 is less than 7 units from zero on the number line.
So, -7 < 2x - 3 < 7
-4 < 2x < 10
-2 < x < 5 Solution set: (-2, 5)
----------------------------------
x2 - x - 12 ≤ 0
(x - 4)(x + 3) ≤ 0
(x - 4)(x + 3) = 0 when x = 4 or -3
When x < -3, both factors are negative, so (x - 4)(x + 3) > 0
When -3 < x < 4, the two factors have opposite signs, so (x - 4)(x + 3) < 0
When x > 4, both factors are positive, so (x - 4)(x + 3) > 0
Solution set [-3, 4]