Chain Rule Derivative
1. **State the problem:** We are given two functions $$f(x) = \sqrt{x}$$ and $$g(x) = x^2 + 7$$ and asked to find the derivative of the composition $$(f \circ g)'(3)$$.
2. **Recall the chain rule:** For functions $f$ and $g$, the derivative of their composition is:
$$ (f \circ g)'(x) = f'(g(x)) \cdot g'(x) $$
3. **Find $f'(x)$:** Since $$f(x) = \sqrt{x} = x^{1/2}$$, the derivative is
$$f'(x) = \frac{1}{2} x^{-1/2} = \frac{1}{2 \sqrt{x}}$$
4. **Find $g'(x)$:** Given $$g(x) = x^2 + 7$$, the derivative is
$$g'(x) = 2x$$
5. **Evaluate $f'(g(3))$:** Calculate $$g(3)$$ first:
$$g(3) = 3^2 + 7 = 9 + 7 = 16$$
Then,
$$f'(g(3)) = f'(16) = \frac{1}{2 \sqrt{16}} = \frac{1}{2 \times 4} = \frac{1}{8}$$
6. **Evaluate $g'(3)$:**
$$g'(3) = 2 \times 3 = 6$$
7. **Calculate $(f \circ g)'(3)$:**
$$ (f \circ g)'(3) = f'(g(3)) \times g'(3) = \frac{1}{8} \times 6 = \frac{6}{8} = \frac{3}{4} $$
8. **Answer:** The value of $$(f \circ g)'(3)$$ is $$\frac{3}{4}$$ which corresponds to option (a).