Derivatives · Exercise 14

Use the definition of derivative $\underset{h\to 0}{\lim }\frac{f\left(x+h\right)-f\left(x\right)}{h}$ to calculate the derivative of each function.

$f\left(x\right)=\sqrt{1+3x}$

Its source prints no answer for this problem, so there's nothing to check against.

OpenStax, Precalculus 2e · §12.4 Derivatives · Exercise 14