As you approach the seventh gate, you notice that it is only a short distance to the area where your computer indicated the communication device was stored. You look past the gate hopefully, as your computer translates: The passcode for this gate is found by determining the domain of the derivative of f (x) and then evaluating the derivative at x=- 77 Enter the domain in interval notation. 26 f(x)=4-26x. Domain of f'(x): 77 ' (-7)