Five' more than twice a
number is -13. find the
number

Step-by-step explanation:

n - a number

five more: + 5

twice a number: 2 · n = 2n

five more than twice a number: 2n + 5

The equation:

2n + 5 = -13           subtract 5 from both sides

2n + 5 - 5 = -13 - 5

2n = -18            divide both sides by 2

2n/2 = -18/2

n = -9

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:

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step-by-step explanation:

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