Step 1: Understanding the Concept
Put \(\sqrt{x} = t\), so \(x = t^2\) and \(dx = 2t\,dt\).
Step 2: Substitute
\(\displaystyle\int\dfrac{dx}{\sqrt{x} + x} = \int\dfrac{2t\,dt}{t + t^2} = \int\dfrac{2\,dt}{1 + t}\).
Step 3: Integrate
\(= 2\log|1 + t| + c = 2\log(1 + \sqrt{x}) + c\).
Final Answer:
The result is \(2\log(1+\sqrt{x}) + c\).
\[ \boxed{\text{(D) }2\log(1+\sqrt{x}) + c} \]