Tina lost 3 pounds on the first week of her diet. she gained a pound on the second week, and then lost 2 pounds a week during every week afterwards. she has been dieting for a total of 13 weeks. how many pounds has tina lost in all?

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:

you never say the total so we cant find the percentage used for petrol

step-by-step explanation: