Question: Using Zeros and y-Intercepts to Sketch a Graph
Consider the function $f(x) = \sqrt{x + 3} + 1$.
a. Find all zeros of $f$.
b. Find the y-intercept (if any).
c. Sketch a graph of $f$.
1. **State the problem:** We are given the function $$f(x) = \sqrt{x + 3} + 1$$ and need to find its zeros, y-intercept, and sketch its graph.
2. **Find the zeros of $f$:**
Zeros occur where $$f(x) = 0$$.
Set the function equal to zero:
$$\sqrt{x + 3} + 1 = 0$$
Subtract 1 from both sides:
$$\sqrt{x + 3} = -1$$
Since the square root function $$\sqrt{x + 3}$$ is always $$\geq 0$$ for its domain, it can never equal $$-1$$.
Therefore, there are **no zeros** of the function.
3. **Find the y-intercept:**
The y-intercept occurs when $$x = 0$$.
Evaluate $$f(0)$$:
$$f(0) = \sqrt{0 + 3} + 1 = \sqrt{3} + 1$$
So the y-intercept is at $$\left(0, \sqrt{3} + 1\right)$$.
4. **Domain of the function:**
The expression inside the square root must be $$\geq 0$$:
$$x + 3 \geq 0 \implies x \geq -3$$
So the domain is $$[-3, \infty)$$.
5. **Sketching the graph:**
- The graph starts at $$x = -3$$.
- At $$x = -3$$, $$f(-3) = \sqrt{-3 + 3} + 1 = 0 + 1 = 1$$.
- The function increases as $$x$$ increases because $$\sqrt{x+3}$$ increases.
- The graph is shifted up by 1 unit compared to $$y = \sqrt{x+3}$$.
- The graph has no zeros and a y-intercept at $$\left(0, \sqrt{3} + 1\right)$$.
**Final answer:**
- No zeros.
- Y-intercept at $$\left(0, \sqrt{3} + 1\right)$$.
- Domain $$[-3, \infty)$$.
- Increasing graph starting at point $$(-3,1)$$ and going upwards.