The model shows the expression 21+9 wich expression is equivalent to this sum

A

Step-by-step explanation:

First way to do this:

3(7 + 3)

7 + 3 = 10

10 multiplied by 3 = 30

Second way to do this:

3(7 + 3)

3 multiplied by 7 = 21

3 multiplied by 3 = 9

21 + 9 = 30

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2

step-by-step explanation:

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: