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C2- Edexcel Help.

Hi,

Can someone tell and explain the best way to tackle this C2 question? I was going to expand everything but thought that would take too long, so was wondering if there is an easier and shorter way of doing it, especially part (a)!

Thanks!
Screen Shot 2018-02-14 at 12.18.18.png22.5KB
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Avatar for Notnek
Notnek
21
Original post by DhylanP - CRGS
Hi,

Can someone tell and explain the best way to tackle this C2 question? I was going to expand everything but thought that would take too long, so was wondering if there is an easier and shorter way of doing it, especially part (a)!

Thanks!

You’ll need to expand (2+x)^5 in the normal way to get the constant, x^2 and x^4 terms but once you’ve done this there isn’t much more work. For (2-x)^5 that’s the same expansion but with x->-x. So the constant, x^2 and x^4 terms will be the same as in the expansion (2+x)^5.

So it’s just a case of expanding one bracket and then doubling the coefficients.
(edited 6 years ago)
once you have found A,B,C... for instance A = -3 B = -11 and C = 8 *FOR ILLUSTRATION ONLY*

then the RHS will be

8x4 - 11x2 - 3

then for part b)

8x4 - 11x2 - 3 = 349
Reply 3
Avatar for 020200
020200
OP
15
Hi,

Would it be best to use the binomial expansion formula and expand to obtain the first 5 terms?

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