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Checking the three-part continuity test at x = 0

Consider the piecewise function v(x)={exx≤0x+1x>0v(x) = \begin{cases} e^x & x \le 0 \\ x + 1 & x > 0 \end{cases}

Use the definition of continuity to determine whether v(x)v(x) is continuous at x=0x = 0. In your answer, state the value of v(0)v(0), the value of lim⁡x→0v(x)\lim_{x \to 0} v(x) (or note if it fails to exist), and whether these two values are equal. Based on this, is vv continuous at x=0x = 0?

Hint

Compute v(0)v(0) directly from the piece that applies at x=0x = 0. Then compute the left-hand limit using exe^x and the right-hand limit using x+1x+1, and compare all three values.

Step-by-step solution

Since x=0x = 0 satisfies x≤0x \le 0, we use v(x)=exv(x) = e^x to get v(0)=e0=1v(0) = e^0 = 1. For the limit, compute the left-hand limit using exe^x: lim⁡x→0−ex=1\lim_{x \to 0^-} e^x = 1. Compute the right-hand limit using x+1x+1: lim⁡x→0+(x+1)=1\lim_{x \to 0^+} (x+1) = 1.

Since both one-sided limits equal 11, lim⁡x→0v(x)=1\lim_{x \to 0} v(x) = 1 exists. Comparing this to v(0)=1v(0) = 1, the limit equals the function value, so all three conditions of continuity are satisfied. Therefore vv is continuous at x=0x = 0.

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