Mark bought gifts for his friends, and each gift cost $9. Let y represent the total cost and represent the number of gifts. Write an equation to represent the proportional relationship between the total cost and the number of gifts he bought. (4 points) Oy=8x a 1 y = 8 x Oy=9x O 1 y = 9 x

y=9x (O 1)

Step-by-step explanation:

9 times the number of gifts he bought which lets say is x will equal your answer (y).

for the points! : )

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: