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Three-part continuity check at x = 3

Consider the piecewise function m(x)={2xx≤3x+5x>3m(x) = \begin{cases} 2^x & x \le 3 \\ x+5 & x > 3 \end{cases}

Use the three-part definition of continuity to determine whether m(x)m(x) is continuous at x=3x=3. In your answer, state the value of m(3)m(3), the value of lim⁡x→3m(x)\lim_{x\to 3} m(x) (if it exists), and whether these two values are equal. Then give your final conclusion: is mm continuous at x=3x=3? If not, classify the discontinuity as removable, jump, or infinite.

Hint

Evaluate m(3)m(3) using the rule for x≤3x\le 3. Then compute the left-hand limit using 2x2^x and the right-hand limit using x+5x+5, both as x→3x\to 3. Compare all three values.

Step-by-step solution

First check f(a)f(a) is defined: since 3≤33\le 3, we use the rule m(x)=2xm(x)=2^x, so m(3)=23=8m(3) = 2^3 = 8. Next check the limit: the left-hand limit uses 2x2^x so lim⁡x→3−m(x)=23=8\lim_{x\to 3^-} m(x) = 2^3 = 8, and the right-hand limit uses x+5x+5 so lim⁡x→3+m(x)=3+5=8\lim_{x\to 3^+} m(x) = 3+5 = 8. Since both one-sided limits exist and are equal, lim⁡x→3m(x)=8\lim_{x\to 3} m(x) = 8.

Finally compare the limit to the function value: lim⁡x→3m(x)=8\lim_{x\to 3} m(x) = 8 and m(3)=8m(3) = 8, so these agree. Since all three conditions of continuity hold (m(3)m(3) is defined, the limit exists, and they are equal), mm is continuous at x=3x=3, and no discontinuity classification applies.

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