Question:medium

If \[ f(x)= \begin{cases} \dfrac{x-2}{|x-2|}+a, & x<2, \\[6pt] a+b, & x=2, \\[6pt] \dfrac{x-2}{|x-2|}+b, & x>2, \end{cases} \] is continuous at \(x=2\), then 

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Always simplify the absolute value term based on whether \( x \) is approaching from the left or right before calculating limits.
Updated On: Jun 13, 2026
  • \( a = 1, b = 1 \)
  • \( a = 1, b = -1 \)
  • \( a = -1, b = 1 \)
  • \( a = -1, b = -1 \)
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The Correct Option is D

Solution and Explanation


Step 1: Understanding the Concept:

For a function to be continuous at \( x = c \), the left-hand limit (LHL), right-hand limit (RHL), and the function value \( f(c) \) must be equal.

Step 2: Detailed Explanation:

1. LHL: \( \lim_{x \to 2^-} (\frac{x-2}{-(x-2)} + a) = -1 + a \).
2. RHL: \( \lim_{x \to 2^+} (\frac{x-2}{x-2} + b) = 1 + b \).
3. Value: \( f(2) = a + b \).
Equating LHL = RHL = \( f(2) \):
\( -1 + a = 1 + b = a + b \).
From \( -1 + a = a + b \), we get \( b = -1 \).
From \( 1 + b = a + b \), we get \( a = 1 \).
Wait, let's re-check: \( -1 + a = a + b \implies b = -1 \). \( -1 + a = 1 + b \implies a - b = 2 \). If \( b = -1 \), then \( a = 1 \). Checking \( f(2) = a + b = 1 - 1 = 0 \).
Setting \( LHL = RHL = f(2) \implies -1+a = 1+b = a+b \).
\( -1+a = a+b \implies b = -1 \).
\( 1+b = a+b \implies a = 1 \).
Result: \( a=1, b=-1 \).

Step 3: Final Answer:

The correct values are \( a = 1, b = -1 \) (Option B).
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