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DE OCR MEI 17th June 2016

Did anyone sit the differential equations exam today who remembers either the mark allocations or the answers for question 1? Thanks xx

Reply 1

username98

was the first part worth 12 marks? another part was worth either 7 or 9, its all a blur hahaha😂

Reply 2

username98

what were your answers, I answered 1 2 and 4

Reply 3

hopefulmedic97

Original post by username98

what were your answers, I answered 1 2 and 4

same. i think 1i) might have been 8 marks but i can't remember how many marks there were for the rest of the parts

Reply 4

username98

Original post by hopefulmedic97

same. i think 1i) might have been 8 marks but i can't remember how many marks there were for the rest of the parts

In question 2, did we have to prove y had a maximum of 1 or a minimum of 1??

Reply 5

hopefulmedic97

minimum. but it said given there is a minimum so you only had to prove it was a stationary point i think

Reply 6

username98

Can you remember any of your answers?? I remember getting something like 0.0108 for eulers, getting 2pi/3 for the last one, but i cant remember the questions for q1 haha

Reply 7

hopefulmedic97

Original post by username98

Can you remember any of your answers?? I remember getting something like 0.0108 for eulers, getting 2pi/3 for the last one, but i cant remember the questions for q1 haha

Yeh I think that's right. Neither lol. I feel like I might have gone wrong in q1

Reply 8

username98

Original post by hopefulmedic97

Yeh I think that's right. Neither lol. I feel like I might have gone wrong in q1

I got te^0.5t as the particular integral for part b but thats all i can remember, need someone to jog my memory loool

Reply 9

hopefulmedic97

Original post by username98

I got te^0.5t as the particular integral for part b but thats all i can remember, need someone to jog my memory loool

I think I got something along the lines of 4e^(-0.5t)+2e^(-1.5t)+te^(-0.5t) for that part. I think for the earlier part I got 4e^(-0.5t)+1.5e^(-1.5t)+0.5e^(0.5t) not completely sure though

Reply 10

username98

Original post by hopefulmedic97

I think I got something along the lines of 4e^(-0.5t)+2e^(-1.5t)+te^(-0.5t) for that part. I think for the earlier part I got 4e^(-0.5t)+1.5e^(-1.5t)+0.5e^(0.5t) not completely sure though

Yeah i got the same, got the stationary point at ln9

Reply 11

username98

Original post by hopefulmedic97

minimum. but it said given there is a minimum so you only had to prove it was a stationary point i think

Do you remember your solution?? I got -1/3sinx-4 I think, deffo had -1 on the top, can't remember the signs on the bottom for sure but one was positive and the other was negative, but when i draw tbis graph it shows a maximum and in the exam I swear my calc showed a minimum so really confused😂

Reply 12

amyjoanne

I think for the proving max of y, it was simply a case of subbing in the max value for sin(x) which is 1. Then you would have -1/3-4 which is 1, and what they wanted you to prove.

Reply 13

amyjoanne

I did questions 1,2,4.Can't remember much but for 1) had constants of 4 and 2 and powers of -1/2, -3/2. Got 0.0108 for eulers method with the same equations as above. For last question i had a solution in terms of of cos and sin t and 2t, and constants of 0 and 1/2. I ended up with a quadratic in sin^2(t) and then has a time of 4pii/3, Did anyone else get these?

Reply 14

16Characters....

If my memory serves me, there were two questions on that paper concerning stationary points which may be the confusion.

In the first question you had to find the value of t of the minimum point of the solution.

In the second question you had to show that 1 is the maximum value of the solution.

Reply 15

username98

Original post by 16Characters....

Haha oh yeah I remember now!! Thanks for clearing that up for me phew😂
For the second question i saw it was only 2 marks but i still did the long method of finding dy/dx, making it equal 0, finding x and then subbing that back in to get 1