Consider the function y = |x| in the interval [-1, 1]. In this interval, the…

1998

Consider the function y = |x| in the interval [-1, 1]. In this interval, the function is

  1. A.

    continuous and differentiable

  2. B.

    continuous but not differentiable

  3. C.

    differentiable but not continuous

  4. D.

    neither continuous nor differentiable

Show answer & explanation

Correct answer: B

The function y = |x| is continuous on the interval [-1, 1] because there are no breaks or jumps in its graph; specifically, the limit as x approaches 0 equals the function value at 0. However, it is not differentiable at x = 0 because the graph has a sharp corner (cusp) at this point. The left-hand derivative is -1, while the right-hand derivative is +1, meaning they do not match. Since differentiability requires a unique tangent line at every point in the interval, the function fails this condition at x = 0. Therefore, while y = |x| is continuous everywhere in the interval, it lacks differentiability at the origin. This makes Option B the correct choice. Options A and C are incorrect because differentiability implies continuity, so a function cannot be differentiable without being continuous. Option D is wrong since the function is clearly continuous throughout [-1, 1].

Explore the full course: Gate Guidance By Sanchit Sir