If 2x + 8 = 0, what justifies 2(x + 4) = 0?

2(x+4)=0

2x+8=0

8-0=2x

8/2=x

4=x

x=4

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:

51

step-by-step explanation:

73-22=51 the   mass number minus the amount of protons gives you the amount of neutrons