Author Topic: C2 DOUBT edexcel  (Read 1106 times)

Offline halosh92

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C2 DOUBT edexcel
« on: February 27, 2010, 07:27:17 am »
(a) Expand (2 + y)^6 in ascending powers of y as far as the term in y^3, simplifying
each coefficient.
(b) Hence expand (2 + x ? x^2)^6 in ascending powers of x as far as the term in x^3,
simplifying each coefficient.

i know how to do the (a) part but am stuck at part (b)
everyday we wake up is a miracle, then how do we say miracles dont happen?????

Offline astarmathsandphysics

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Re: C2 DOUBT edexcel
« Reply #1 on: February 27, 2010, 09:41:57 am »
Can you restate the question?

Offline halosh92

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Re: C2 DOUBT edexcel
« Reply #2 on: February 27, 2010, 10:02:09 am »
Can you restate the question?

how do u do the second part?
everyday we wake up is a miracle, then how do we say miracles dont happen?????

Offline astarmathsandphysics

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Re: C2 DOUBT edexcel
« Reply #3 on: February 27, 2010, 10:17:27 am »
I meant this (2 + x ? x^2)^6
with the question mark in the middle

Offline halosh92

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Re: C2 DOUBT edexcel
« Reply #4 on: February 27, 2010, 02:53:49 pm »
I meant this (2 + x ? x^2)^6
with the question mark in the middle

sorry typing mistake its:
(2+ x- x^2)^6
everyday we wake up is a miracle, then how do we say miracles dont happen?????

Offline astarmathsandphysics

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Re: C2 DOUBT edexcel
« Reply #5 on: February 27, 2010, 04:58:15 pm »
Ok will do it when I get home

Offline astarmathsandphysics

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Re: C2 DOUBT edexcel
« Reply #6 on: February 27, 2010, 06:36:55 pm »
(2+x)^6=1*2^6*x^0+6*2^5*x^1+15*2^4*x^2+20*2^3*x^3+....
=64+192x+240x^2+160x^3....
Now replace all the x's by x-x^2
64+192(x-x^2)+240(x-x^2)^2 +160(x-x^2)^3
64-192x-192x^2+240(x^2-2x^3)+160x^3 ignoring all powers of x higher than x^3
=64+192x+48x^2-320x^3

Offline halosh92

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Re: C2 DOUBT edexcel
« Reply #7 on: February 28, 2010, 12:54:59 pm »
(2+x)^6=1*2^6*x^0+6*2^5*x^1+15*2^4*x^2+20*2^3*x^3+....
=64+192x+240x^2+160x^3....
Now replace all the x's by x-x^2
64+192(x-x^2)+240(x-x^2)^2 +160(x-x^2)^3
64-192x-192x^2+240(x^2-2x^3)+160x^3 ignoring all powers of x higher than x^3
=64+192x+48x^2-320x^3

ok thankyou!!!! :D ;)
everyday we wake up is a miracle, then how do we say miracles dont happen?????