STEP question need help quick :)
[h="1"]Show that the coefficient of x^-12 in the expansion of (X^4 - 1/X^2)^5 * (X-1/x)^6 is -15, and calculate the coefficent of x^2. This is a STEP question, for REALLY clever ppl to help me real quick thanks lads
[/h]
[/h]Cmon guys, need help!! i mean, if i do this by binomial, this would be a pain in the arse. but is there a quicker way?
Original post by chenghan626
[h="1"]Show that the coefficient of x^-12 in the expansion of (X^4 - 1/X^2)^5 * (X-1/x)^6 is -15, and calculate the coefficent of x^2. This is a STEP question, for REALLY clever ppl to help me real quick thanks lads[/h]
[/h]Try posting in the Maths Forum and showing your working and someone will point out where you have gone wrong.
Show that the coefficient of x^-12 in the expansion of (X^4 - 1/X^2)^5 * (X-1/x)^6 is -15, and calculate the coefficent of x^2. This is a STEP question, for REALLY clever ppl to help me real quick thanks lads
Original post by chenghan626Show that the coefficient of x^-12 in the expansion of (X^4 - 1/X^2)^5 * (X-1/x)^6 is -15, and calculate the coefficent of x^2. This is a STEP question, for REALLY clever ppl to help me real quick thanks lads
Show that the coefficient of x^-12 in the expansion of (X^4 - 1/X^2)^5 * (X-1/x)^6 is -15, and calculate the coefficent of x^2. This is a STEP question, for REALLY clever ppl to help me real quick thanks ladsAs I just explained to you in the A Level forum you need to show YOUR working. We will then point out where you have gone wrong. TSR is not a homework service.
Original post by Mr M
As I just explained to you in the A Level forum you need to show YOUR working. We will then point out where you have gone wrong. TSR is not a homework service.
this isn't home work lol, i just have no idea how to do this.
Original post by chenghan626
this isn't home work lol, i just have no idea how to do this.
Yes you do. You have already mentioned binomial expansions.
Original post by chenghan626
this isn't home work lol, i just have no idea how to do this.
Well, how would you normally work out binomial expansions and multiply them together?
You can save a little time by thinking about what powers of x you're going to get from each bracket and which ones need to be combined to get the required power, then just focus on the coefficients of those terms.
Ok lads I'll try checking my workings and see where I've gone wrong
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Original post by chenghan626
Cmon guys, need help!! i mean, if i do this by binomial, this would be a pain in the arse. but is there a quicker way?
You've got another thread open for this and I've just made a comment in that one.
Tbh if you're tackling STEP seriously you should be prepared for a lot more algebra than this
Original post by davros
You've got another thread open for this and I've just made a comment in that one.
Are you sure?
I'm just starting my first year in AS. And just starting to do some STEPs. Picking the ones that I think I can do lol
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Yeah sure. Cheers man thanks a lot
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Original post by chenghan626
I'm just starting my first year in AS. And just starting to do some STEPs. Picking the ones that I think I can do lol
You might be biting off more than you can chew at this stage. The clue is in the name SIXTH TERM examination paper.
Original post by Mr M
Are you sure?
Yes I noticed someone's cunning attempt to confuse me as soon as my last update was posted!
Original post by Mr M
You might be biting off more than you can chew at this stage. The clue is in the name SIXTH TERM examination paper.
I think it's only fair to point out that that doesn't mean the OP should defer his preparation until the Sixth Term
Original post by davros
I think it's only fair to point out that that doesn't mean the OP should defer his preparation until the Sixth Term
First Term. Sixth Term. Meeting somewhere in the middle would be ok.
Original post by Mr M
First Term. Sixth Term. Meeting somewhere in the middle would be ok.
I would suggest the time to start is C4 completion + "x amount of maturity" where x varies by candidate
This assumes of course that the candidate has the good sense to get to the end of C4 in advance - ideally by the Fourth Term (and of course some schools will teach full A2 in Y12 so it won't be an issue).
Original post by chenghan626
[h="1"]Show that the coefficient of x^-12 in the expansion of (X^4 - 1/X^2)^5 * (X-1/x)^6 is -15, and calculate the coefficent of x^2. This is a STEP question, for REALLY clever ppl to help me real quick thanks lads[/h]
[/h]Evaluate only the possible powers which result in -12 which speeds up the process very quickly as it ignores irrelevant algebra and powers of x.
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