52577011
Let \(u(x)=\sqrt{x+2}\) and \(v(x)=e^x\). Find equations for \(f=u\circ v\) and \(g=v\circ u\), including the maximal real domain of each composition.
Hints
- Substitute the entire inner function into the outer function.
- Check both the domain of the inner function and the input restrictions of the outer function.
- Recall the domains of exponential and square-root functions.
Solution
1. For \(f=u\circ v\), \(f(x)=u(v(x))=\sqrt{e^x+2}\). Since \(e^x>0\) for every real \(x\), the radicand is always positive. Therefore, \(D_f=\mathbb{R}\).
2. For \(g=v\circ u\), \(g(x)=v(u(x))=e^{\sqrt{x+2}}\). The square root requires \(x+2\ge0\), so \(D_g=[-2, \infty)\).
Answer
\(f(x)=\sqrt{e^x+2}\), \(D_f=\mathbb{R}\)
\(g(x)=e^{\sqrt{x+2}}\), \(D_g=[-2, \infty)\)
