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Edexcel A2 C3 Mathematics 12th June 2015

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Original post by studentwiz
how do you find the max of 2root5sin(3thetha-1.107)^2


Well the Max value will be when sin3theta-1.107 is 1. So what would the min value be?

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Original post by samb1234
Well the Max value will be when sin3theta-1.107 is 1. So what would the min value be?

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0 ? I got 104 max and 4 minbut how would you do part ii and c ii?
Reply 522
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Viggi
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Anyone know why if you have dy/dx= -e^x you get a gradient of -1???? thanks!! :smile: :smile: (I'm finding your posts reeeeaaally helpful!)
anyone bothering learning proof by contradiction etc. considering they've never actually come up in an exam?
Original post by broconomist
anyone bothering learning proof by contradiction etc. considering they've never actually come up in an exam?


Is it even on the syllabus?

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Original post by studentwiz
0 ? I got 104 max and 4 minbut how would you do part ii and c ii?


They would be the values of theta such that sintheta =1 or sin theta =0 respectively

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Original post by Krollo
Is it even on the syllabus?

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there's a section in the textbook that I have (cambridge C3 A2 maths for edexcel) which is concerned with proof by contradiction, definite proofs etc. I've only seen one question on it though and that was on an elmwood paperScreen Shot 2015-05-22 at 18.11.51.png
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Viggi
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Original post by broconomist
there's a section in the textbook that I have (cambridge C3 A2 maths for edexcel) which is concerned with proof by contradiction, definite proofs etc. I've only seen one question on it though and that was on an elmwood paperScreen Shot 2015-05-22 at 18.11.51.png


Good to know! :smile: thanks!
Original post by broconomist
there's a section in the textbook that I have (cambridge C3 A2 maths for edexcel) which is concerned with proof by contradiction, definite proofs etc. I've only seen one question on it though and that was on an elmwood paperScreen Shot 2015-05-22 at 18.11.51.png


Its not on the spec never done any of that and its not in the heinman book which I believe is the official textbook

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Original post by samb1234
They would be the values of theta such that sintheta =1 or sin theta =0 respectively

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thanks ive done part b but part cii) the answer is 2.46 and i got 0.123 can you explain what im doing wrong please
Original post by samb1234
Its not on the spec never done any of that and its not in the heinman book which I believe is the official textbook

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yeah that's what I'm hoping for, but if you look on this: http://www.waldomaths.com/docs/edex/C3_Edex_6665_Spec.pdf

"Methods of proof, including proof by contradiction and disproof bycounter-example, are required."
Original post by Viggi
Anyone know why if you have dy/dx= -e^x you get a gradient of -1???? thanks!! :smile: :smile: (I'm finding your posts reeeeaaally helpful!)


You only get that when x=0
Reply 532
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Viggi
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Original post by Mr T Pities You
You only get that when x=0


*lightbulb* ...I understand now... :P
I doubt proof by contradiction would come up....ever. But knowing Edexcel this year and how hellbent they are to prove to the world that A levels are not easy at all, they might sneak it in and come up with some random twisted reason for how it is in the specification -_-
Reply 534
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Viggi
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ok, another question - what is the rule behind e^1/2ln9 becoming e^ln3 ? ... thanks!!!
Original post by studentwiz
thanks ive done part b but part cii) the answer is 2.46 and i got 0.123 can you explain what im doing wrong please


What's the rsinalpha form?

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Original post by broconomist
there's a section in the textbook that I have (cambridge C3 A2 maths for edexcel) which is concerned with proof by contradiction, definite proofs etc. I've only seen one question on it though and that was on an elmwood paperScreen Shot 2015-05-22 at 18.11.51.png


It isn't on the syllabus, but that's a very nice question. (I assume you're meant to consider the parity of the factors?)


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Original post by Guitardude165
I doubt proof by contradiction would come up....ever. But knowing Edexcel this year and how hellbent they are to prove to the world that A levels are not easy at all, they might sneak it in and come up with some random twisted reason for how it is in the specification -_-


my sentiments exactly!
Original post by Viggi
ok, another question - what is the rule behind e^1/2ln9 becoming e^ln3 ? ... thanks!!!


Using Log rules (power one specifically) raise the 1/2 up to the 9 which becomes √9 (using indice laws) and therefore that becones 3. So e^1/2ln9 = e^ln3
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Viggi
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Original post by broconomist
my sentiments exactly!


It has been really tough!!

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