Look for r 5(x - 4) + 4 + r = 4(x + 3) + x

Simplifying

5[x + -4] + 4 + r = 4[x + 3] + x

Reorder the terms:

5[-4 + x] + 4 + r = 4[x + 3] + x

[-4 * 5 + x * 5] + 4 + r = 4[x + 3] + x

[-20 + 5x] + 4 + r = 4[x + 3] + x

Reorder the terms:

-20 + 4 + r + 5x = 4[x + 3] + x

Combine like terms: -20 + 4 = -16

-16 + r + 5x = 4[x + 3] + x

Reorder the terms:

-16 + r + 5x = 4[3 + x] + x

-16 + r + 5x = [3 * 4 + x * 4] + x

-16 + r + 5x = [12 + 4x] + x

Combine like terms: 4x + x = 5x

-16 + r + 5x = 12 + 5x

Add '-5x' to each side of the equation.

-16 + r + 5x + -5x = 12 + 5x + -5x

Combine like terms: 5x + -5x = 0

-16 + r + 0 = 12 + 5x + -5x

-16 + r = 12 + 5x + -5x

Combine like terms: 5x + -5x = 0

-16 + r = 12 + 0

-16 + r = 12

Solving

-16 + r = 12

Solving for variable 'r'.

Move all terms containing r to the left, all other terms to the right.

Add '16' to each side of the equation.

-16 + 16 + r = 12 + 16

Combine like terms: -16 + 16 = 0

0 + r = 12 + 16

r = 12 + 16

Combine like terms: 12 + 16 = 28

r = 28

Simplifying

r = 28

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: