1. **State the problem:** We are given two functions:
$$f(x) = \frac{e^{2x} + 2e^{x} + 2}{e^{x} + 1}$$
and
$$g(x) = \ln|x|$$
We need to find the inverse of the composition \((f \circ g)^{-1}(x)\), which means find the inverse function of \(f(g(x))\).
2. **Write the composition:**
$$ (f \circ g)(x) = f(g(x)) = f(\ln|x|) = \frac{e^{2\ln|x|} + 2e^{\ln|x|} + 2}{e^{\ln|x|} + 1} $$
Recall that \(e^{\ln|x|} = |x|\), so:
$$ (f \circ g)(x) = \frac{|x|^{2} + 2|x| + 2}{|x| + 1} $$
3. **Simplify the numerator:**
$$ |x|^{2} + 2|x| + 2 = (|x| + 1)^{2} + 1 $$
So,
$$ (f \circ g)(x) = \frac{(|x| + 1)^{2} + 1}{|x| + 1} $$
4. **Divide numerator by denominator:**
$$ (f \circ g)(x) = \frac{\cancel{(|x| + 1)}(|x| + 1) + 1}{\cancel{|x| + 1}} = |x| + 1 + \frac{1}{|x| + 1} $$
5. **Set \(y = (f \circ g)(x)\):**
$$ y = |x| + 1 + \frac{1}{|x| + 1} $$
Let \(t = |x| + 1 > 0\), then:
$$ y = t + \frac{1}{t} $$
6. **Solve for \(t\):**
Multiply both sides by \(t\):
$$ yt = t^{2} + 1 $$
Rearranged:
$$ t^{2} - yt + 1 = 0 $$
7. **Use quadratic formula:**
$$ t = \frac{y \pm \sqrt{y^{2} - 4}}{2} $$
Since \(t = |x| + 1 > 0\), we take the positive root:
$$ t = \frac{y + \sqrt{y^{2} - 4}}{2} $$
8. **Find \(|x|\):**
$$ |x| = t - 1 = \frac{y + \sqrt{y^{2} - 4}}{2} - 1 $$
9. **Find \(x\):**
Since \(g(x) = \ln|x|\), the domain of \(g\) is \(x \neq 0\), and \(f \circ g\) depends on \(|x|\), the inverse will have two branches:
$$ x = \pm \left( \frac{y + \sqrt{y^{2} - 4}}{2} - 1 \right) $$
10. **Express the inverse function:**
$$ (f \circ g)^{-1}(x) = \pm \left( \frac{x + \sqrt{x^{2} - 4}}{2} - 1 \right) $$
**Final answer:**
$$ (f \circ g)^{-1}(x) = \pm \left( \frac{x + \sqrt{x^{2} - 4}}{2} - 1 \right) $$
This gives the inverse of the composition function for \(x \geq 2\) (since \(y^{2} - 4 \geq 0\) for real values).
Inverse Composition 01D9F6
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