Mathematics

Mathematics

Problem

Consider the function f(x)={sin⁡x,x<0,x,x≥0.f(x)=\begin{cases} \sin x, & x<0,\\ x, & x\ge 0. \end{cases} Explain briefly whether ff is continuous at x=0x=0 and why.
Intuitive explanation

Continuity at a point hinges on whether the left and right limits match the function value there. Here, you need to check if lim⁡x→0−sin⁡x\lim_{x \to 0^-} \sin x, lim⁡x→0+x\lim_{x \to 0^+} x, and f(0)f(0) all agree. Since sin⁡x\sin x approaches 00 as x→0−x \to 0^- and xx approaches 00 as x→0+x \to 0^+, while f(0)=0f(0) = 0 by definition, all three match—so the function is continuous at x=0x=0.

Intuitive explanation

Continuity at a point hinges on whether the left and right limits match the function value there. Here, you need to check if lim⁡x→0−sin⁡x\lim_{x \to 0^-} \sin x, lim⁡x→0+x\lim_{x \to 0^+} x, and f(0)f(0) all agree. Since sin⁡x\sin x approaches 00 as x→0−x \to 0^- and xx approaches 00 as x→0+x \to 0^+, while f(0)=0f(0) = 0 by definition, all three match—so the function is continuous at x=0x=0.

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