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Help: Factorization

How is the following equation possible?

\[ x^3 - 6x - 40 = (x-4)(x^2+4x+10) \]

I forgot

Note by Jason Chrysoprase
7 months, 1 week ago

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\(x^3-6x-40 \\ = x^3-4x^2+4x^2-16x+10x-40 \\ = x^2(x-4)+4x(x-4)+10(x-4) \\ = (x-4)(x^2+4x+10)\)

Its not something to memorize to forget though :P Nihar Mahajan · 7 months, 1 week ago

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@Nihar Mahajan Thanks Nihar, it was quite helpful. Sandeep Bhardwaj · 7 months, 1 week ago

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@Nihar Mahajan \( x^3 - 6x - 40 \\ = x^3 \color{red}{- 4x^2 + 4x^2 - 16x + 10x} - 40 \)

How did you get those red numbers ? Jason Chrysoprase · 7 months, 1 week ago

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@Jason Chrysoprase So that we can factor out \((x-4)\) from each pair. Nihar Mahajan · 7 months, 1 week ago

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@Nihar Mahajan thx mate Jason Chrysoprase · 7 months, 1 week ago

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@Nihar Mahajan I'm felling silly now XD

I'm 13 Jason Chrysoprase · 7 months, 1 week ago

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