1. **State the problem:** We want to find values of $a$ and $b$ such that the piecewise function
$$
f(x) = \begin{cases}
\frac{1}{x} & x < -1 \\
ax + b & -1 \leq x \leq \frac{1}{2} \\
\frac{1}{x} & x > \frac{1}{2}
\end{cases}
$$
is continuous everywhere.
2. **Recall the continuity condition:** A function is continuous at a point if the left-hand limit, right-hand limit, and the function value at that point are all equal.
3. **Check continuity at $x = -1$:**
- Left limit: $\lim_{x \to -1^-} f(x) = \lim_{x \to -1^-} \frac{1}{x} = \frac{1}{-1} = -1$
- Right limit: $\lim_{x \to -1^+} f(x) = a(-1) + b = -a + b$
- Function value: $f(-1) = a(-1) + b = -a + b$
Set left and right limits equal for continuity:
$$
-1 = -a + b
$$
4. **Check continuity at $x = \frac{1}{2}$:**
- Left limit: $\lim_{x \to (1/2)^-} f(x) = a\left(\frac{1}{2}\right) + b = \frac{a}{2} + b$
- Right limit: $\lim_{x \to (1/2)^+} f(x) = \frac{1}{\frac{1}{2}} = 2$
- Function value: $f\left(\frac{1}{2}\right) = a\left(\frac{1}{2}\right) + b = \frac{a}{2} + b$
Set left and right limits equal for continuity:
$$
\frac{a}{2} + b = 2
$$
5. **Solve the system of equations:**
$$
\begin{cases}
-a + b = -1 \\
\frac{a}{2} + b = 2
\end{cases}
$$
From the first equation:
$$
b = a - 1
$$
Substitute into the second:
$$
\frac{a}{2} + (a - 1) = 2
$$
Simplify:
$$
\frac{a}{2} + a - 1 = 2
$$
$$
\frac{3a}{2} = 3
$$
$$
a = 2
$$
Then,
$$
b = 2 - 1 = 1
$$
**Final answer:**
$$
a = 2, \quad b = 1
$$
Piecewise Continuity
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