Step 1 :Substitute \(g(x)\) into \(f(x)\) to get \(f(g(x)) = f\left(\frac{7}{x}\right) = \frac{\frac{7}{x}}{\frac{7}{x} + 3}\)
Step 2 :Multiply the numerator and the denominator by \(x\) to simplify the expression: \(f(g(x)) = \frac{7}{7 + 3x}\)
Step 3 :Set the denominator equal to zero and solve for \(x\) to find the domain: \(7 + 3x = 0\) gives \(x = -\frac{7}{3}\)
Step 4 :The domain of \(f(g(x))\) is all real numbers except \(-\frac{7}{3}\). In interval notation, this is \((-\infty, -\frac{7}{3}) \cup (-\frac{7}{3}, \infty)\)
Step 5 :\(\boxed{(f \circ g)(x) = \frac{7}{7 + 3x}}\)
Step 6 :\(\boxed{\text{Domain of } f \circ g: (-\infty, -\frac{7}{3}) \cup (-\frac{7}{3}, \infty)}\)