I don't understand how to do this problem, can you please help me?

Question

Given the functions f and g, determine the domain of f+g.

4. f(x)= 2x/(x-3) g(x)=3/(x+6)

Answer 1

That would be the set of real numbers x that result in real values for f + g

For f(x) by itself, the domain is all numbers except 3. For g(x), the domain is all numbers except -6.

For f + g, the domain is all numbers from -infinity to +infinity except -6 and 3.

Answer 2

For further reading I suggest

http://www.analyzemath.com/DomainRange/DomainRange.html