The scatter plot shows how many books were sold at a book store during the first fifteen days of a summer vacation. If a relationship exists, make a conjecture about the number of books that will be sold on the 17th day of the summer vacation. a.
7 books

b.
35 books

c.
20 books

d.
no relationship exists

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:

3 is greater then both of those numbers