Daniel K.

asked • 01/10/16

Binomial Theorem

Find the term independent of x in the expansion of (1+x+x-3)7.

1 Expert Answer

By:

Daniel K.

nope your answer is totally wrong. what the question wants is after you expand, what is the independent term of x.
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01/11/16

Arnold F.

Is the question asking for the constant term after the expansion is performed?
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01/11/16

Brian O.

tutor
I assume the question is asking for the constant term because it is only this term is independent of x.  In Binomial expansion only the constant term is independent from x other terms would have x in it.
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01/11/16

Daniel K.

The question is asking for the constant term after the expansion is performed. So can u worked it out?
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01/11/16

Brian O.

tutor
Expanding (1+x+x-3)*7 = 7 + 7x + 7x-3
Expanding (1+x+x-3)7 is more complicated and has to use Binomial Expansion to do it.
But if our focus is to find the term which does not have x, then we may rewrite the expansion as below:
[1+(x + x-3)]7 = 1 + 7(x + x-3) + 21(x + x-3)2 + 35(x + x-3)3 + 35(x + x-3)4+ 21(x + x-3)5+7(x + x-3)6+(x + x-3)7
Only the first term 1 is independent of x
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01/11/16

Daniel K.

Nope. The answer is 141.
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01/11/16

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