Piecewise Limits 02648E
1. **State the problem:** We have a piecewise function
$$h(z) = \begin{cases} 6z & \text{if } z \leq -4 \\ 1 - 9z & \text{if } z > -4 \end{cases}$$
We need to find:
(a) $\lim_{z \to 7} h(z)$
(b) $\lim_{z \to -4} h(z)$
2. **Recall the limit rules for piecewise functions:**
- To find the limit at a point, check the function's value as $z$ approaches from the left and right.
- If both one-sided limits are equal, the limit exists and equals that value.
- If they differ, the limit does not exist (DNE).
3. **Evaluate (a) $\lim_{z \to 7} h(z)$:**
- Since $7 > -4$, use the second piece: $h(z) = 1 - 9z$
- The function is continuous here, so
$$\lim_{z \to 7} h(z) = 1 - 9(7) = 1 - 63 = -62$$
4. **Evaluate (b) $\lim_{z \to -4} h(z)$:**
- Left-hand limit ($z \to -4^-$): use $6z$
$$\lim_{z \to -4^-} h(z) = 6(-4) = -24$$
- Right-hand limit ($z \to -4^+$): use $1 - 9z$
$$\lim_{z \to -4^+} h(z) = 1 - 9(-4) = 1 + 36 = 37$$
- Since $-24 \neq 37$, the limit at $z = -4$ does not exist.
**Final answers:**
(a) $\lim_{z \to 7} h(z) = -62$
(b) $\lim_{z \to -4} h(z) = \text{DNE}$