Piecewise Limit Continuity
1. **Problem Statement:** We have a piecewise function $$g(t) = \begin{cases} \frac{1}{2}t + 1 & \text{if } t < 2 \\ \sqrt{t} - 2 & \text{if } t \geq 2 \end{cases}$$
We need to:
a. Determine if the limit exists at $t = -2$.
b. Determine if the limit exists at $t = 3$.
c. Check if $g(t)$ is continuous throughout its domain.
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2. **Recall the limit definition:** The limit of $g(t)$ as $t$ approaches $a$ exists if and only if the left-hand limit (LHL) and right-hand limit (RHL) at $a$ exist and are equal.
3. **Part a: Limit at $t = -2$**
- Since $-2 < 2$, we use the first piece $g(t) = \frac{1}{2}t + 1$ for values near $-2$.
- Calculate the limit:
$$\lim_{t \to -2} g(t) = \lim_{t \to -2} \left( \frac{1}{2}t + 1 \right) = \frac{1}{2}(-2) + 1 = -1 + 1 = 0$$
- Because the function is defined by the same expression on an open interval around $-2$, the limit exists and equals 0.
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4. **Part b: Limit at $t = 3$**
- Since $3 \geq 2$, we use the second piece $g(t) = \sqrt{t} - 2$ for values near 3.
- Calculate the limit:
$$\lim_{t \to 3} g(t) = \lim_{t \to 3} (\sqrt{t} - 2) = \sqrt{3} - 2$$
- The function is defined by the same expression on an open interval around 3, so the limit exists and equals $\sqrt{3} - 2$.
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5. **Part c: Continuity of $g(t)$ throughout its domain**
- A function is continuous at a point if:
1. The function is defined at that point.
2. The limit exists at that point.
3. The limit equals the function value at that point.
- For $t < 2$ and $t > 2$, each piece is continuous because they are linear and square root functions respectively.
- Check continuity at $t = 2$ (the boundary):
- Left-hand limit (LHL):
$$\lim_{t \to 2^-} g(t) = \lim_{t \to 2^-} \left( \frac{1}{2}t + 1 \right) = \frac{1}{2}(2) + 1 = 1 + 1 = 2$$
- Right-hand limit (RHL):
$$\lim_{t \to 2^+} g(t) = \lim_{t \to 2^+} (\sqrt{t} - 2) = \sqrt{2} - 2 \approx 1.414 - 2 = -0.586$$
- Since LHL $\neq$ RHL, the limit at $t=2$ does not exist.
- Also, $g(2) = \sqrt{2} - 2 \approx -0.586$.
- Because the limit does not exist at $t=2$, $g(t)$ is **not continuous** at $t=2$.
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**Final answers:**
- a. The limit at $t = -2$ exists and equals 0.
- b. The limit at $t = 3$ exists and equals $\sqrt{3} - 2$.
- c. The function $g(t)$ is not continuous at $t = 2$ but continuous elsewhere in its domain.