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# Edexcel A2 C4 Mathematics June 2015 - Official Thread watch

1. (Original post by Anon-)
$\int 2sin^{2}x\cdot cosx\, dx$
What would be most efficient/intuitive way to integrate this? It came up in an Edexcel paper and they didn't give any information on which method to use, and in the mark scheme they didn't even show the steps for intergrating it.
Recongnition

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2. u=sinx
du/dx=cosx
dx=du/cosx
so the integral turns to 2u^2 as the cosx cancels out.
No limits to change
So the integral is 2/3 u^3
which is 2/3 sin^3x

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3. (Original post by lam12)
Recognition, any tips then what to look out for in order to do it?

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Look at the differntial of each funcion. Consider the power to a higher power. Then divide by this new power and add a minus sign if needed

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4. If you've got two lines, one with the gradient 1 and the other with the gradient 1/3, how is this the gradient between them?
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5. Picture didn't work
6. Hi can anyone help me with part a? I'm a bit confused on what the the question is asking you to do?
7. Helloooo!
Do you needs to know the proofs for:
a.b = b.a
and
a.(b + c) = a.b + a.c

It's in my text book but I don't know if we have to be able to fully recall it?
Thanks!
8. (Original post by LMottram)
Helloooo!
Do you needs to know the proofs for:
a.b = b.a
and
a.(b + c) = a.b + a.c

It's in my text book but I don't know if we have to be able to fully recall it?
Thanks!
I'm pretty sure you don't need to know it

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9. (Original post by Elliemay97)
Hi can anyone help me with part a? I'm a bit confused on what the the question is asking you to do?
Its just asking how you'd set up the integral. So to find the area of R you'd need to use ∫y.dx/dt. Which will then get you to the answer it wants you to show.

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10. (Original post by ooftar)
Its just asking how you'd set up the integral. So to find the area of R you'd need to use ∫y.dx/dt. Which will then get you to the answer it wants you to show.

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First mark is for saying r= integral of y dx
Then differentiate x and find what dt is. Put it in and simplify.

Change the bounds too

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11. cant do b
12. (Original post by Yua)

cant do b
When x=0 g(x)=3 look at the graph 3>g(x)>0
13. (Original post by Medicjug)
When x=0 g(x)=3 look at the graph 3>g(x)>0
But g(x) can never go below 1/2 as x tends to infinity so it'd be 3 >= g(x) > 1/2

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14. (Original post by skyakdu)
But g(x) can never go below 1/2 as x tends to infinity so it'd be 3 >= g(x) > 1/2

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15. Let The Games Commence

Alright Guys Lets Quit The Small Talk Now. I am asking for one thing, and one thing only!:
5 TOP tips on how to ace this exam
When i say ace, I don't mean a measly 65/75, I don't even mean a sky-high 70 (giving a god damn a*), I am talking 73/75. You heard right people 73 the stuff of dreams.
Best answer will gain my full approval, I shall also owe that sir/Madame my life
16. (Original post by Wahid1)

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How exactly?

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17. (Original post by skyakdu)
How exactly?

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That **** is c3

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18. (Original post by NightAl96)
Let The Games Commence

Alright Guys Lets Quit The Small Talk Now. I am asking for one thing, and one thing only!:
5 TOP tips on how to ace this exam
When i say ace, I don't mean a measly 65/75, I don't even mean a sky-high 70 (giving a god damn a*), I am talking 73/75. You heard right people 73 the stuff of dreams.
Best answer will gain my full approval, I shall also owe that sir/Madame my life
come on guys I haven't got all day!
well I do but no more than 1 day cos the exams tomorrow
19. (Original post by NightAl96)
come on guys I haven't got all day!
well I do but no more than 1 day cos the exams tomorrow
No it's not its on Tuesday

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20. (Original post by Wahid1)
No it's not its on Tuesday

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C3s tomorrow

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