CBSE Class 12 Mathematics Continuity and Differentiability Q #1383
COMPETENCY BASED
APPLY
2 Marks 2025 AISSCE(Board Exam) VSA
Check the differentiability of f(x) at $x=-2$ if $f(x)=\begin{cases}2x-3,-3\le x\le-2\\ x+1,-2

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Detailed Solution

Step 1: Understand the condition for differentiability

A function $f(x)$ is differentiable at $x=a$ if the Left Hand Derivative (LHD) equals the Right Hand Derivative (RHD) at that point. That is, $LHD = RHD$.

Step 2: Calculate the Left Hand Derivative (LHD)

For $x < -2$, $f(x) = 2x - 3$. The derivative $f'(x) = 2$. Thus, the LHD at $x = -2$ is: $$LHD = \lim_{h \to 0} \frac{f(-2-h) - f(-2)}{-h} = 2$$

Step 3: Calculate the Right Hand Derivative (RHD)

For $x > -2$, $f(x) = x + 1$. The derivative $f'(x) = 1$. Thus, the RHD at $x = -2$ is: $$RHD = \lim_{h \to 0} \frac{f(-2+h) - f(-2)}{h} = 1$$

Step 4: Compare LHD and RHD

Since $LHD = 2$ and $RHD = 1$, we observe that $LHD \neq RHD$. Therefore, the function is not differentiable at $x = -2$.

Final Answer: The function is not differentiable at x = -2.

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Pedagogical Audit
Bloom's Analysis: This is an APPLY question because the student must apply the formal definition of derivatives to a piecewise function to verify continuity and differentiability.
Knowledge Dimension: PROCEDURAL
Justification: The question requires executing a specific algorithmic process (calculating LHD and RHD) to reach a conclusion.
Syllabus Audit: In the context of CBSE Class 12, this is classified as COMPETENCY. This tests the core conceptual understanding of calculus limits and differentiability, which is a fundamental topic in the Continuity and Differentiability chapter.