SOLUTION: factor completely..... 3x4-81x=

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Question 212746: factor completely..... 3x4-81x=
Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Factor completely:
3x%5E4-81x First, factor out 3x from each term.
3x%28x%5E3-27%29 Notice that the binomial in the parentheses is the difference of two cubes.
3x%28%28x%29%5E3-%283%29%5E3%29
The difference of two cubes is factorable thus:
A%5E3-B%5E3+=+%28A-B%29%28A%5E2%2BAB%2BB%5E2%29, so...
3x%28%28x%29%5E3-%283%29%5E3%29+=+highlight%283x%28x-3%29%28x%5E2%2B3x%2B9%29%29