Question

Ex 8
Dau coroana e urgent!!

Answer 1

a)

A={x ∈ R | |x| ≤ 5}

|x| ≤ 5⇒

⇒x ≤ 5

⇒x ≤ -5

x ∈ [-5,5]

b)

B={x ∈ R | |x| - 1 < 7}

|x|-1<7 / +1

|x| < 8⇒

⇒x < 8

⇒x < -8

x ∈ (-8,8)

c)

C={ x ∈ R | |x-5| < 1}

|x-5| < 1

x-5 < 1 /+5

x < 6

sau

x-5 < -1 /+5

x < 4

⇒

x ∈ (4,6)

d)

D={ x ∈ R | |2x-3| ≤ 11}

2x-3 ≤ 11 / +3

2x ≤ 14 / :2

x ≤ 7

sau

2x-3 ≤-11/+3

2x ≤ -8 / :2

x ≤ -4

x ∈ [-4,7]