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Maths Ocr 2016 C1

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Original post by KevinGu123456789
For the question about the circle being wholly inside the other, did anyone else get 0<r<√45 - 5?
Most people got 0<r<2, but I thought that this may not be right


I got this, as did most other people at my school who managed to answer it.
Reply 61
Original post by KevinGu123456789
Does anyone remember the actual last question though?


Wasn't it something like y=4x^2+a/x+5 and y has a stationary point at which the y coordinate = 32.

I differentiated to find 8x-a/x^2 and then equated to 0. Then said that 8x^3-a=0 therefore 8x^3=a.

Plug that back into the original equation to get 32=4x^2+8x^2+5 (32 is the y coordinate we were given).

Solving that to get x= 0 and + or - 3/2. Then plugging that back in to the original equation gave a=0, not possible or a negative solution when it asked for the positive solution so solving that eventually gave 27.

I hope that makes sense? Think it's correct (I BLOODY HOPE SO!)
Reply 62
I got y=2x-20 and y=2x+10 for tangents of circles
Yep. Deffo just got nearly every question wrong.
Original post by AlfieH
Can anybody remember the indices questions? I remember the first one was (2^5 divided by 2^7) but there was something else in that question.

Also - what about the 2nd question, I got -¼+or-¾root5


Yep, myself and at least 4 others got the same answer for the second question
How did people get 27? I got 27/12 fek
Reply 66
Original post by Dmitry_Mednov
It is wrong as if you use k as -5 or -6 it will not intersect the curve, I checked it at the end.


He's right, you're wrong. b^2-4ac when K<-7.5 was a number less than zero. Above -7.5 it gave a positive number, so when K<-7.5 ether are no real roots to the equation and the lines do not cross, you probably subbed it in wrong.

That paper wasn't hard.
Can someone explain how they did the last question?
Original post by AlfieH
Can anybody remember the indices questions? I remember the first one was (2^5 divided by 2^7) but there was something else in that question.

Also - what about the 2nd question, I got -¼+or-¾root5


Yeah that's right
Original post by duncant
I got y=2x-20 and y=2x+10 for tangents of circles


same man
Reply 70
Original post by KevinGu123456789
For the question about the circle being wholly inside the other, did anyone else get 0<r<√45 - 5?
Most people got 0<r<2, but I thought that this may not be right


I got that! I said the radius was 3√5 whereas lots thought it was 2√5.

Thing is on that question the distance from Centre to 0,0 was 5 therefore the radius couldn't have been 2√5 so I quickly changed that!

I got 0<r<3√5-5 (same as you).
Original post by nobodycarescarla
How did people get 27? I got 27/12 fek


8(27/12)^3/2 simplifies to 27
Original post by julesaquilina
I got k is less than -2 and greater than 5? And many others got that as well

I got that as well😊
With the indice questions, was it 2^-6 for part (i) and 2^13/3 for (ii)?
Original post by AlfieH
Wasn't it something like y=4x^2+a/x+5 and y has a stationary point at which the y coordinate = 32.

I differentiated to find 8x-a/x^2 and then equated to 0. Then said that 8x^3-a=0 therefore 8x^3=a.

Plug that back into the original equation to get 32=4x^2+8x^2+5 (32 is the y coordinate we were given).

Solving that to get x= 0 and + or - 3/2. Then plugging that back in to the original equation gave a=0, not possible or a negative solution when it asked for the positive solution so solving that eventually gave 27.

I hope that makes sense? Think it's correct (I BLOODY HOPE SO!)


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i think the grade boundaries will be in the 50s for an A - i found january 2011 a lot easier and it was 54 for an A
Reply 76
A=27 for last question. Y=1/16 and y=8 for hidden quadratic. K less than -2 but great than 5 for question 9. Y=(x-2)^2 (5-x) for translation.
Reply 77
Original post by JackA123
With the indice questions, was it 2^-6 for part (i) and 2^13/3 for (ii)?


I got 2^-6 but was worrying cos all I remember from the exam is 2^5 divided by 2^7 which gives ¼ so there must've been something else I can't remember.

Mathematically speaking should be a 2^-4...
question 9 was x^2 + 2x + 11= k(2x-1), find k

and 11 was y= 4x^2 + a/x + 5, find a, also when dy/dx=o, y=32
Reply 79
Original post by duncant
A=27 for last question. Y=1/16 and y=8 for hidden quadratic. K less than -2 but great than 5 for question 9. Y=(x-2)^2 (5-x) for translation.


(x-2)^2 (5-x)?

I put x^2(5-x) If it was (x-2)^2 it would've also resulted in a stretch.

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