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OCR Maths Core 2 - May 25th 2016

A1998lebanna

Did anyone get question 9 in the last bit ?

Reply 1

Tom2907

I didn't in the exam but i know how to now.. you had to differentiate P and set it equal to 0 to find the x value, then sub that into the P equation to get the minimum perimeter. For e) you differentiate your first differential and sub in your x value, then this will be a positive number showing that is it minimum

Reply 2

alig348

wrong exam mate, I think ur talking about the edexcel c2 exam

Reply 3

gsdfghgfhfg

What did you get for Q9 A AND K
A=3/5
K=√3 / 2 ??????

(edited 7 years ago)

Reply 4

alig348

yh i got that buy I dont know if its right, what did u get for the last question

Reply 5

Hiling99

Original post by A1998lebanna

Did anyone get question 9 in the last bit ?

I think I got pi/3a and 4pi/3a but I can't remember for certain.

Reply 6

Bruce267099

Original post by Hiling99

I think I got pi/3a and 4pi/3a but I can't remember for certain.

I got the same :biggrin:

. I just completely guessed.

Reply 7

lou_16

Am i the only one who really struggled with that exam? 😂 lol well ive failed maths

Reply 8

Maths genius 420

Hiya guys,

Im an online tutor and just read over the paper and Q9 seemed to be a rough question if you didnt quite swat up on your trigonometry haha! Anyways your answers are both correct for the 2 parts of Q9 from what I see : )! Great Job haha!

1pi/3a and 4pi/3a

My answers:

1. 10
5.04

2. 3Pi/10
20.4

3. 27 + 27kx + 9k^2x^2 + k^3x^3
K= (root 3). K = -(root 3)

4. Log3 (X^2/X + 4)
X = -3. X = 12

5. (X^4/2) - X^3 + 2X^2 - 6X + C
(4a^2 - 6a + 2)a^2
4

6. K = 91
562
N = 38

7. Q = X^2 - 4X + 3. R = 0
X = -1. X = 1. X = 3
Stationary points are given by (dy/dx) = 0
512/15

8. Translation by +2 along X axis
Stretch by 1/9 in Y direction
Intersection with Y axis at (0,1/9)
6.73
9.60

9. Period is 2Pi/a
a = 5/3. K = (root 3)/2
Pi/3a. 4Pi/3a

Reply 11

dvfdsv

Isn't A 3/5? AS then this scale factor is applied, it then turns in 5/3?

i.e A=3/5 so when applied The values becomes sin(5/3 x) and so 5/3 mulitplied by PI/5 gives you pi/3 which is the correct answer?

Because K=Root3/2

so A must be the inverse of the values?

Reply 12

dvfdsv

Sorry you missread isnt A 3/5?

Reply 13

mrsweg59

Youre wrong. the answer is 5/3.

(edited 7 years ago)

Reply 14

_.lukeg._

Original post by gsdfghgfhfg

What did you get for Q9 A AND K
A=3/5
K=√3 / 2 ??????

I got a = 5/3 ?? A lot of my friends got that as well

Reply 15

Stephen65golf

Original post by _.lukeg._

I got a = 5/3 ?? A lot of my friends got that as well

How did you arrive at your answer, i am struggling to work it out.

Reply 16

Stephen65golf

Can some please help and explain how you arrived at your answers to question 9 ii and iii

Reply 17

_.lukeg._

Original post by Stephen65golf

How did you arrive at your answer, i am struggling to work it out.

I'm not going to remember now am I hahaha

Reply 18

intue14

Original post by Stephen65golf

Can some please help and explain how you arrived at your answers to question 9 ii and iii

i). y = sin (ax). This is a stretch by 1/a in the x direction. Therefore the period is 2Pi/a

ii). x = Pi/5 and x = 2Pi/5. Therefore sin(aPi/5) = k and sin(a2Pi/5) = k
1/2(2Pi/5 - Pi/5) = Pi/10 Pi/5 + Pi/10 = 3Pi/10
(3Pi a)/10 maps to Pi/2 because of the stretch in the x direction so a = 10/6 = 5/3. (It's much easier to show on a diagram! The way you have to think of it is that there is a 'solution' either side of Pi/2).
Sin((5/3)(Pi/5)) = Root3/2. And Sin((5/3)(2Pi/5)) = Root3/2

iii). Sin(ax) = Root3Cos(ax). So Tan(ax) = Root3. Therefore ax = Pi/3

X = Pi/3a, 4Pi/3a (x is positive but gives a negative solution), 7Pi/3a

Hope this helps.

(edited 7 years ago)

Reply 19

Stephen65golf

Original post by intue14