Tip:A–D to answerE for explanationV for videoS to reveal answer
The value of x satisfies the inequality |x –1| + |x –2| > 4 if
Correct Answer: x∈(−∞, −21)∪[27, ∞)
Explanation
Case 1: x≥2
For x≥2:
∣x−1∣=x−1
∣x−2∣=x−2
(x - 1) + (x - 2) > 4
2x - 3 > 4
2x > 7
x > \tfrac{7}{2}
\textbf{Case 2: } 1 < x < 2
\text{For } 1 < x < 2:
∣x−1∣=x−1
∣x−2∣=2−x
(x - 1) + (2 - x) > 4
1 > 4
No solution in interval (1,2)
Case 3: x≤1
For x≤1:
∣x−1∣=1−x
∣x−2∣=2−x
(1 - x) + (2 - x) > 4
3 - 2x > 4
-2x > 1
x < -\tfrac{1}{2}
Explanation
Case 1: x≥2
For x≥2:
∣x−1∣=x−1
∣x−2∣=x−2
(x - 1) + (x - 2) > 4
2x - 3 > 4
2x > 7
x > \tfrac{7}{2}
\textbf{Case 2: } 1 < x < 2
\text{For } 1 < x < 2:
∣x−1∣=x−1
∣x−2∣=2−x
(x - 1) + (2 - x) > 4
1 > 4
No solution in interval (1,2)
Case 3: x≤1
For x≤1:
∣x−1∣=1−x
∣x−2∣=2−x
(1 - x) + (2 - x) > 4
3 - 2x > 4
-2x > 1
x < -\tfrac{1}{2}