Question
Mathematics Question on linear inequalities
If ∣x+5∣≥10 , then
A
x∈(−15,5]
B
x∈(−5,5]
C
x∈(−∞,−15]∪[5,∞)
D
x∈[−∞,−15]∪[5,∞)
Answer
x∈(−∞,−15]∪[5,∞)
Explanation
Solution
Given ∣x+5∣≥10
⇒x+5≤−10 or x+5≥10
⇒x≤−15 or x≥5
⇒x∈(−∞,−15]∪[5,∞)
If ∣x+5∣≥10 , then
x∈(−15,5]
x∈(−5,5]
x∈(−∞,−15]∪[5,∞)
x∈[−∞,−15]∪[5,∞)
x∈(−∞,−15]∪[5,∞)
Given ∣x+5∣≥10
⇒x+5≤−10 or x+5≥10
⇒x≤−15 or x≥5
⇒x∈(−∞,−15]∪[5,∞)