Check Identify each as an equation or and expression.
21x-13 +11
Equations
Expressions
x= 2x+5
-3.7x-13
12x + 5
12x = 5 + 3
3x + 1 = -2.1

Step-by-step explanation:

An equation contains a sign equality (=) between two expressions.

And an expression is a simple algebraic statement.

By these definitions,

          Equations                          Expressions

         x = 2x + 5                            21x - 13 + 11x

                                    -3.7x - 13  

         3x + 1 = -2.1                          

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: