Which phrase describes a nonlinear function?

•a) the area of a circle as a function of the radius.

•b) the perimeter of a square as a function of the side length.

•c) the cost of gasoline as a function of the number of gallons purchased.

•d) the distance traveled by a car moving at the constant speed as a function of time.

42

step-by-step explanation:

256/6=42

since your problem is x^4 = 81, what you have to undeo is the "to the fourth power" part.

the inverse (opposite operation) of "to the fourth power" is "to the fourth root".

  (x^4) ^ ¼   = 81 ^ ¼  

  81 = 3^4     so (3 ^ 4) ^ ¼   =   3 ^ 1   = 3

by hand: (3 ^ 4) ^ ¼   =   3 ^ (4 x ¼) = 3 ^ 1   = 3   (when you take a power to a power, multiply the exponents.)

or, do it by calculator. one way of finding the fourth root is to use ^ (1/4)

step-by-step explanation: