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Edexcel Core 3 - 21st June 2016 AM

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Original post by sabahshahed294
But why do exactly substitute the first and second derivatives? Any reason?


Well, you're being asked to show that the equation is true for that function. In order to do that you have to sub in the derivatives for that function

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Original post by pineneedles
Well, you're being asked to show that the equation is true for that function. In order to do that you have to sub in the derivatives for that function

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I see. Thank you! :smile:
Anyone know what thr last 4 formulas under trig identities are? Havent learnt those?
Original post by Don Pedro K.
I'm assuming the range is 0 < x < 360.

cot2x = 1/tan2x

so 1/tan2x = 0

When you flip it over to get tan2x on top, you are doing 0/0 ---> 0/0 = undefined. So you're basically looking at wherever there are asymptotes on the y = tanx graph. This is where x = 90 and 270 for tanx. So, for tan2x, it's 45 and 135 degrees because you divide 90 and 270 by two :smile:

Thats a good way of doing it,

I expanded cot(2theta), ended up geting tan(theta)=+/- 1 and getting the solutions
How is everyone balancing C3 and C4 revision?
Original post by kosvengali
How is everyone balancing C3 and C4 revision?


I've pretty much done c3 just gonna got 2014-2016 papers to do
For c4 I still need to do all the gold papers then go over all the mistakes I made then do 2014-2016


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Do you need to learn the proof of Tan(A+B) ?


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Original post by Don Joiner
Do you need to learn the proof of Tan(A+B) ?


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Using sin(A+B) and cos(A+B), yes it has come up before.
Original post by kosvengali
How is everyone balancing C3 and C4 revision?


precariously xD
How do I simplify 2e^(ln(2)+3) ?? Thanks
Original post by NotoriousS
How do I simplify 2e^(ln(2)+3) ?? Thanks


Use the rule ab+c=ab×aca^{b+c} =a^b\times a^c
Can someone explain to me what this question means..

Given that the equation f(x) = k where k is a constant, has exactly two roots.
state the range of possible values of k.

What does that mean?
What are all the proofs i need to know for this exam?

cheers
Original post by Lilly1234567890
Can someone explain to me what this question means..

Given that the equation f(x) = k where k is a constant, has exactly two roots.
state the range of possible values of k.

What does that mean?


Are you given f(x)?
Find real values of λ and μ such that:



If anyone has a go, please spoiler solutions :smile:
Original post by Euclidean
Find real values of λ and μ such that:



If anyone has a go, please spoiler solutions :smile:


What even is this o.O? Is this another crazy thing that us mere mortals aren't expected to know how to do?
Original post by Don Pedro K.
Are you given f(x)?


As in generally, because i have seen a question like it. shall i found one?
Original post by Don Pedro K.
What even is this o.O? Is this another crazy thing that us mere mortals aren't expected to know how to do?


I think once the method is clearer it becomes quite an interesting result, if you need a hint:

Spoiler

Further Hint:

Spoiler

Original post by Lilly1234567890
As in generally, because i have seen a question like it. shall i found one?


Well, usually when you want to show that something has exactly two roots, you show that the discriminant (b)^2 - 4ac > 0. If you can find an example, please let me know!
Original post by Euclidean
Find real values of λ and μ such that:



If anyone has a go, please spoiler solutions :smile:


I haven't made a proper go at it (should be revising not going back to try tricky a level stuff lol) but on playing around with stuff I find it depends on the values of theta which seems to not be what was intended..

Spoiler

(edited 7 years ago)

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