Sketch the graph of the piecewise function and write the domain in interval notation.
\[
f(x)=\left\{\begin{array}{ll}
x-3 & \text { if } x<-1 \\
-3 x+1 & \text { if } x \geq-1
\end{array}\right.
\]
Graph \(f(x) = x - 3\) for \(x < -1\).
Choose two \(x\) values less than \(-1\), say \(-3\) and \(-2\).
When \(x = -3\), \(f(-3) = -3 - 3 = -6\). The point is \((-3, -6)\).
When \(x = -2\), \(f(-2) = -2 - 3 = -5\). The point is \((-2, -5)\).
Plot the points and draw a ray that starts at \((-1, -4)\) with an open circle and passes through the two points.
Graph \(f(x) = -3x + 1\) for \(x \geq -1\).
Choose two \(x\) values greater than or equal to \(-1\), say \(-1\) and \(0\).
When \(x = -1\), \(f(-1) = -3(-1) + 1 = 4\). The point is \((-1, 4)\).
When \(x = 0\), \(f(0) = -3(0) + 1 = 1\). The point is \((0, 1)\).
Plot the points and draw a ray that starts at \((-1, 4)\) with a closed circle and passes through the point \((0, 1)\).
Write the domain in interval notation.
The first piece is defined for \(x < -1\) and the second piece is defined for \(x \geq -1\). Combining these, we get the domain of all real numbers.
Domain: \((-\infty, \infty)\)
The graph is shown below with an open circle at \((-1,-4)\) and a closed circle at \((-1,4)\).
The domain of the piecewise function is \((-\infty, \infty)\).
The graph consists of two rays, one starting at \((-1, -4)\) with an open circle and extending to the left, and the other starting at \((-1, 4)\) with a closed circle and extending to the right.
The domain of the piecewise function is \(\boxed{(-\infty, \infty)}\).