Answer:
a)
![f'(x) = m](https://img.qammunity.org/2021/formulas/mathematics/college/geq049cso60tb3gl2riz78k05jgmtff5ad.png)
b)
![x \in (-\infty, \infty)](https://img.qammunity.org/2021/formulas/mathematics/college/2sgb40n3vusyac9h5jixvil6s7dz3ekcgy.png)
c)
![x \in (-\infty, \infty)](https://img.qammunity.org/2021/formulas/mathematics/college/2sgb40n3vusyac9h5jixvil6s7dz3ekcgy.png)
Explanation:
We are given the following in the question:
![f(x) = mx + q](https://img.qammunity.org/2021/formulas/mathematics/college/7ch95b5esjrjnffifgek7ymdek7p72fnob.png)
a) We have to find the derivative of the given function.
![f'(x) = (f(x+h)-f(x))/(h)\\\\= (m(x+h)+q - mx - q)/(h)\\\\f'(x) = (mh)/(h)\\\\f'(x) = m](https://img.qammunity.org/2021/formulas/mathematics/college/ozztzi2pcwo49dhyoryflex6wkm1yd65si.png)
b) Domain of f(x)
Domain is the collection of all values of x for which the function is defined.
Domain of f(x) is all real numbers.
![x \in (-\infty, \infty)](https://img.qammunity.org/2021/formulas/mathematics/college/2sgb40n3vusyac9h5jixvil6s7dz3ekcgy.png)
c) Domain of f'(x)
Domain of f'(x) is all real numbers.
![x \in (-\infty, \infty)](https://img.qammunity.org/2021/formulas/mathematics/college/2sgb40n3vusyac9h5jixvil6s7dz3ekcgy.png)