Given A = |x + 3| + |x - 2| - |2x - 8|. The maximum value of |A| is:
Explanation:
A = |x + 3| + |x - 2| - |2x - 8|
The critical points are -3, 2 and 4.
Case 1: x ≥ 4 ∴ A = x + 3 + x - 2 - (2x - 8) ⇒ A = 2x + 1 - 2x + 8 ⇒ A = 9
Case 2: 2 ≤ x < 4 ∴ A = x + 3 + x - 2 + (2x - 8) ⇒ A = 2x + 1 + 2x - 8 ⇒ A = 4x - 7 ∴ A ∈ [1, 9)
Case 3: -3 ≤ x < 2 ∴ A = x + 3 - (x - 2) + (2x - 8) ⇒ A = x + 3 - x + 2 + 2x - 8 ⇒ A = 2x - 3 ∴ A ∈ [-9, 1)
Case 4: x < -3 ∴ A = - (x + 3) - (x - 2) + (2x - 8) ⇒ A = - x - 3 - x + 2 + 2x - 8 ⇒ A = - 9
From the above cases, The maximum value of |A| = 9
Hence, option (b).
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