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**romani****Member**- Registered: 2013-06-28
- Posts: 3

hello! so, I've came accross a problem I can't solve at all :c. The problem is as it follows:

**The constant term of **

I searched how to solve it and found only one solution, but I didn't understand what was done... they turned

into and somehow found that k = 2. also, they found "", which give us a = -3.That's actually the right answer, but I can't figure out what was done to solve this problem... :c Can you guys explain it to me?

Thanks c:

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**bob bundy****Moderator**- Registered: 2010-06-20
- Posts: 6,378

hi romani

Welcome to the forum.

This involves the binomial theorem. Do you know this?

Bob

You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,302

Hi;

Welcome to the forum.

The expansion of that is

from which you see 10a^3 is the constant term.

10 a^3 = - 270

a^3 = - 27

a = -3

Or:

Your latexing did not come out.

That is derived from the binomial theorem. You only have to solve the equation.

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

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**romani****Member**- Registered: 2013-06-28
- Posts: 3

Oh, of course! I was making a really stupid mistake.

Sorry for bothering you with such a silly question!

Thank you very much for helping me! c:

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**bobbym****Administrator**- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 86,302

No bother, happens to me all the time.

**In mathematics, you don't understand things. You just get used to them.Of course that result can be rigorously obtained, but who cares?Combinatorics is Algebra and Algebra is Combinatorics.**

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