Let $f(x) = (x+2)^2 - 2$, $x \geq -2$. If $g(x)$ is a function whose graph is reflection of the graph of $y = f(x)$ in the line $y = x$, then $g(x)$ is equal to:
Step-by-Step Solution
Key Concept: Reflection of a function in $y=x$ gives the inverse function.
Step 1: Understand what reflection in the line $y = x$ means.
The reflection of the graph of $y = f(x)$ in the line $y = x$ gives us the inverse function $g(x) = f^{-1}(x)$. Therefore, we need to find the inverse of the given function.
Step 2: Set up the equation to find the inverse function.
Let $y = f(x)$, so:
$$y = (x+2)^2 - 2$$
To find the inverse, we need to solve for $x$ in terms of $y$.
Step 3: Isolate the squared term.
Add 2 to both sides:
$$y + 2 = (x+2)^2$$
Step 4: Take the square root of both sides.
$$\sqrt{y+2} = |x+2|$$
Since we are given that $x \geq -2$, we have $x + 2 \geq 0$. Therefore, we take the positive square root:
$$\sqrt{y+2} = x + 2$$
Step 5: Solve for $x$.
Subtract 2 from both sides:
$$x = \sqrt{y+2} - 2$$
Step 6: Write the inverse function by swapping variables.
In the inverse function $g(x) = f^{-1}(x)$, we replace $y$ with $x$ and $x$ with $g(x)$:
$$g(x) = \sqrt{x+2} - 2$$
Step 7: State the final answer.
The function $g(x)$ whose graph is the reflection of $y = f(x)$ in the line $y = x$ is:
$$g(x) = \sqrt{x+2} - 2$$
This matches **Option 3**.
Correct Answer: 3