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WJEC C1, Binomials.

At the moment I'm having trouble with working out the coefficients and powers, I was hoping someone would be able to help by pointing me to some good tutorials or giving some tips themselves.

Any advice is welcomed, thanks.

Here are some examples of questions I'm having trouble with:
January 2012- The coefficient of x^2 in the expansion of (1 + 2x)^n is 760. Given that n is a positive integer, find the value of n.

May 2011- In the binomial expansion of (1 + x/4)^n, the coefficient of x^2 is five times the coefficient of x.Given that n is a positive integer, find the value of n.

May 2010-
(a) Write down the expansion of (1 + x)^6 in ascending powers of x up to and including the term in x^3. (This I understand, it's the next question that troubles me).


(b) By substituting an appropriate value for x in your expansion in (a), find an approximate value for 0·99^6. Show all your working and give your answer correct to four decimal places.
Jan 2012

Write down the expansion of (1+2x)n(1+2x)^n as far as the term in x2x^2. It should then be obvious what to do.

May 2011

Follow the same approach.

May 2010

So 1−x=0.991-x=0.99

What value must x take?
Aah I remember this paper:

Expand up until x^2 term.

Then use that co efficient and equal it to 760.

Remember that the x term isn't x. But 2x. That's key in this.

Then it's a quadratic in disguise :smile:

You'll have two solutions, only.one is viable, due to the restraint made.

∫−iiiidx\displaystyle\int_{-i}^{i} i^{i} dx
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Lelipops
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Thanks a lot guys!
Original post by Lelipops
Thanks a lot guys!


Did you get 20? :smile:

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