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Classifying the discontinuity of v(x) at x = 0

Consider the function v(x)={sin⁡(x)xx≠02x=0v(x) = \begin{cases} \dfrac{\sin(x)}{x} & x \neq 0 \\ 2 & x = 0 \end{cases}

Using the fact that lim⁡x→0sin⁡(x)x=1\lim_{x \to 0} \dfrac{\sin(x)}{x} = 1, determine whether v(x)v(x) is continuous at x=0x = 0. If it is discontinuous, state which of the three parts of the continuity definition fails, and classify the discontinuity as removable, jump, or infinite.

Hint

Check the three conditions in order: is v(0)v(0) defined, does lim⁡x→0v(x)\lim_{x\to 0} v(x) exist, and if so, does it equal v(0)v(0)? Compare the limit value to the given function value at 00.

Step-by-step solution

First check the three conditions for continuity at x=0x=0. We are told v(0)=2v(0) = 2, so the function value is defined. Next, lim⁡x→0v(x)=lim⁡x→0sin⁡(x)x=1\lim_{x\to 0} v(x) = \lim_{x\to 0} \frac{\sin(x)}{x} = 1, since for x≠0x \neq 0 near 00 the function agrees with sin⁡(x)/x\sin(x)/x, so the limit exists and equals 11.

Now compare the limit to the function value: lim⁡x→0v(x)=1\lim_{x\to 0} v(x) = 1, but v(0)=2v(0) = 2, so these are not equal. Since f(a)f(a) is defined and the limit exists but they disagree, the third condition of continuity fails, and this is a removable discontinuity — the graph has a hole at (0,1)(0,1) that could be patched by redefining v(0)=1v(0) = 1.

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