SOLUTION: Nine more than the cube of a number is the same as 81 times the number. Find the numbers.

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Question 1053105: Nine more than the cube of a number is the same as 81 times the number. Find the numbers.
Answer by Boreal(15235) About Me  (Show Source):
You can put this solution on YOUR website!
the number is x
x^3+9=81x
x^3-81x+9=0
graph%28300%2C300%2C-10%2C10%2C-100%2C100%2Cx%5E3-81x%2B9%29
0.111128 is one zero; cube of that plus 9=9.0014. 0.111128*81 is 9.0014
-9.055 is a second zero. Cube of that +9 is -733.45, -9.055*81 is -733.46
8.9439 is the third zero. Cube that and add 9 and get 724.452 8.9439*81 is 724.456