SOLUTION: I want to factorise this polynom x^3 - 8 The answer should be (x - 2 )(x^2 + 2x + 4) I want to know the method please Thank you

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Question 537712: I want to factorise this polynom
x^3 - 8

The answer should be (x - 2 )(x^2 + 2x + 4)
I want to know the method please
Thank you
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!

x%5E3-8 Start with the given expression.


%28x%29%5E3-%282%29%5E3 Rewrite x%5E3 as %28x%29%5E3. Rewrite 8 as %282%29%5E3.


%28x-2%29%28%28x%29%5E2%2B%28x%29%282%29%2B%282%29%5E2%29 Now factor by using the difference of cubes formula. Remember the difference of cubes formula is A%5E3-B%5E3=%28A-B%29%28A%5E2%2BAB%2BB%5E2%29


%28x-2%29%28x%5E2%2B2x%2B4%29 Multiply

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Answer:
So x%5E3-8 factors to %28x-2%29%28x%5E2%2B2x%2B4%29.

In other words, x%5E3-8=%28x-2%29%28x%5E2%2B2x%2B4%29


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