We are given the functions:
f(x) = 4 x – 5 ---> 1
g(x) = 3 x + 7 ---> 2
To find for the value of f(x) + g(x), all we have to do is to add equations 1 and 2:
f(x) + g(x) = 4 x – 5 + 3 x + 7
f(x) + g(x) = 7 x + 2 = y
In this case, for any real number value assign to x, we get a real number value of y. This is because the function is linear.
Therefore the domain of the function is all real numbers.