Answer:
Correct option: first one
Step-by-step explanation:
The equation f(x) = 5x + 1 is a function, because each value of x gives only one value of y.
Now let's find the inverse by switching f(x) by x and x by f'(x), then isolating f'(x):
The inverse f'(x) is also a function, because each value of x gives only one value of x.
So we have that both the equation and its inverse are function, therefore the correct answer is the first option.