WBJEE · Maths · Continuity and Differentiability

Let \(f(x)=|1-2 x|\), then

A \(f(x)\) is continuous but not differentiable at \(x=\frac{1}{2}\)
B \(f(x)\) is differentiable but not continuous at \(x=\frac{1}{2}\)
C \(f(x)\) is both continuous and differentiable at \(x=\frac{1}{2}\)
D \(f(x)\) is neither differentiable nor continuous at \(x=\frac{1}{2}\)

Verified Solution

Answer & Solution

Correct Answer

(A) \(f(x)\) is continuous but not differentiable at \(x=\frac{1}{2}\)

Step-by-step Solution

Detailed explanation

The absolute value function can be rewritten as a piecewise function: \(f(x)= \begin{cases}1-2 x, & \text { if } x \leq \frac{1}{2} \\ -(1-2 x), & \text { if } x>\frac{1}{2}\end{cases}\) 2. Check for continuity at \(x=\frac{1}{2}\) : Left-hand limit:…

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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