Question

Solve |2x + 1| = 10

Answer 1

By definition of absolute value we have two equalities:
 2x + 1 = 10
 2x + 1 = -10
 For 2x + 1 = 10:
 2x + 1 = 10
 2x = 10-1
 2x = 9
 x = 9/2
 For 2x + 1 = -10:
 2x + 1 = -10
 2x = -10-1
 2x = -11
 x = -11 / 2
 Answer:
 {-11/2, 9/2}