Final Answer
Step-by-step Solution
Problem to solve:
Find the derivative of $x$ using the definition. Apply the definition of the derivative: $\displaystyle f'(x)=\lim_{h\to0}\frac{f(x+h)-f(x)}{h}$. The function $f(x)$ is the function we want to differentiate, which is $x$. Substituting $f(x+h)$ and $f(x)$ on the limit
Simplify the fraction $\frac{h}{h}$ by $h$
The limit of a constant is just the constant