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Edexcel Core 3 - 21st June 2016 AM

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Avatar for boyyo
boyyo
6
Original post by NotNotBatman
Use the Factor theorem for the numerator.


How did you know to do that straight away? I spent like 10 minutes trying to divide the numerator by the denominator >_<
Original post by boyyo
How did you know to do that straight away? I spent like 10 minutes trying to divide the numerator by the denominator >_<


I always try to break it down first. It's the difference of two cubes, so it factorises.
Reply 302
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boyyo
6
Original post by NotNotBatman
I always try to break it down first. It's the difference of two cubes, so it factorises.


ahh right, okay thanks:smile:
Original post by boyyo
https://b3755649dbd1afe3db91a899c3b9837b22326254.googledrive.com/host/0B1ZiqBksUHNYMG14YWtobVJUUms/for-Edexcel/Solomon%20K%20QP%20-%20C3%20Edexcel.pdf

Can someone help me with q2b here. Im not getting the right answer when I do long division and I dont quite understand what the mark scheme does
Thanks


What I did first was factorise the bottom to give (3x-2)(x-2). I then used the (x-2) as a clue as to what is gonna appear in the numerator. So, I checked to see if x =2 is a factor of the numerator, which it was, so I did long division using (x-2) as the divisor (bit outside the bus shelter).

So you get (x-2)(x^2 + 2x + 4) as the numerator, (3x-2)(x-2) as the denominator --> cancel out the (x-2) and badabing badaboom you've got your answer :smile:
Reply 304
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boyyo
6
Original post by Don Pedro K.
What I did first was factorise the bottom to give (3x-2)(x-2). I then used the (x-2) as a clue as to what is gonna appear in the numerator. So, I checked to see if x =2 is a factor of the numerator, which it was, so I did long division using (x-2) as the divisor (bit outside the bus shelter).

So you get (x-2)(x^2 + 2x + 4) as the numerator, (3x-2)(x-2) as the denominator --> cancel out the (x-2) and badabing badaboom you've got your answer :smile:


Lol thanks man :biggrin:
Original post by Don Pedro K.
What I did first was factorise the bottom to give (3x-2)(x-2). I then used the (x-2) as a clue as to what is gonna appear in the numerator. So, I checked to see if x =2 is a factor of the numerator, which it was, so I did long division using (x-2) as the divisor (bit outside the bus shelter).

So you get (x-2)(x^2 + 2x + 4) as the numerator, (3x-2)(x-2) as the denominator --> cancel out the (x-2) and badabing badaboom you've got your answer :smile:


Is there a general for diff of. 2 Cubes you need to know
Original post by metrize
Is there a general for diff of. 2 Cubes you need to know


Dunno ask @NotNotBatman :smile:
Original post by metrize
Is there a general for diff of. 2 Cubes you need to know


You don't need to know it, but it is: a3−b3=(a−b)(a2+ab+b2) a^3-b^3 = (a-b)(a^2 +ab+b^2), you could just use the factor thereom, but my first clue was because it was the difference of two cubes and that's how I knew the top factorises.
Are doing papers other than the regular edexcel ones (IYGB/Solomon) essential for getting 90UMS?


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Original post by Don Joiner
Are doing papers other than the regular edexcel ones (IYGB/Solomon) essential for getting 90UMS?


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definitely not
Reply 310
Avatar for pauux
pauux
2
Basically i messed up in the M1 paper and now i need to get at least 95 UMS in this exam, anyone has any tips 😭 ?
I'm stuck on this question, I managed to get an equation with tanx and tan40 in it though 1466017747479.jpg
1466017761574.jpg

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Original post by pineneedles
I'm stuck on this question, I managed to get an equation with tanx and tan40 in it though 1466017747479.jpg
1466017761574.jpg

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ImageUploadedByStudent Room1466018444.891383.jpg


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Original post by Supermanxxxxxx


I can't work out what you did when you went from the second line to the third line?


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Original post by pineneedles
I can't work out what you did when you went from the second line to the third line?


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I used the substitutions shown below the 3rd line


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Original post by Supermanxxxxxx
I used the substitutions shown below the 3rd line


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Are we just supposed to 'know' that sin40 = cos50?:confused:

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Original post by pineneedles
Are we just supposed to 'know' that sin40 = cos50?:confused:

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I assume so or if you just put it in your calculator you would have figured it out


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Original post by pineneedles
Are we just supposed to 'know' that sin40 = cos50?:confused:

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cos(α) = sin(90-α)

same goes for the other way round:

sin(β) = cos(90-β)
If we were trying to find out <ABC (just as an example) in a vector question.

Do we do

1) BA.BC=BA.BCcosA
2)AB.CB=AB.BCcosA

Basically are we using BA/BC or AB/BC because we end up with different answers.

thanks
Original post by Lilly1234567890
If we were trying to find out <ABC (just as an example) in a vector question.

Do we do

1) BA.BC=BA.BCcosA
2)AB.CB=AB.BCcosA

Basically are we using BA/BC or AB/BC because we end up with different answers.

thanks


BA, BC, use vectors that point away from the angle.

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