Find the derivative using the chain rule. \[ f(k)=\sqrt{2 k^{9}+7} \] Show your work here Hint: To add the square root symbol $(\sqrt{\square})$, type "root"

Step 1 ：Find the derivative of the function using the chain rule: \(f'(k) = \frac{1}{2\sqrt{2k^9 + 7}} \cdot 18k^8\)

Step 2 ：Simplify the expression: \(f'(k) = \frac{9k^8}{\sqrt{2k^9 + 7}}\)

Step 3 ：Evaluate the derivative for a given value of k (e.g., k = 2): \(f'(2) \approx 71.755\)

Step 4 ：\(\boxed{f'(k) = \frac{9k^8}{\sqrt{2k^9 + 7}}}\)