STEP 2016 Solutions

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Reply 140

username1258398

q3 Solution

Spoiler

(edited 7 years ago)

Reply 141

MathHysteria

Seriously, has nobody got a copy of the paper? I want to get my teeth into it over the weekend!

Reply 142

Ewanclementson

Here is my solution to Q10; a real gem of a question (both short and easy).

Reply 143

username1162972

Original post by StrangeBanana

q3 Solution

Spoiler

Exactly how i did the question with explanation on the complex roots aswell with some justification odd degree polynomials have atleast 1 root hence exactly 1 since this has atmost one.

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Reply 144

username1258398

Original post by physicsmaths

Exactly how i did the question with explanation on the complex roots aswell with some justification odd degree polynomials have atleast 1 root hence exactly 1 since this has atmost one.

awesum

Yeah I was trying to be succinct in the solution, in the exam I was more careful. I think you might need to mention that there can't be repeated roots, though.

$x$

Anyone willing to estimate my marks?

1) (Curve C1 and C2 one) Done completely.
3) (f_n(x) polynomial one) Got all of it, except at the very end I didn't explain why f_n(x)=0 has 0 roots if n is even and 1 root if odd (I just stated that there's 0 roots if n even and 1 root if n odd).
4) Got all of it except I couldn't find x and tan(theta) in part (iii).
6) (Differential Equation one) Got all of it except part (iii).
8) (Approximating sum from r=1 to r=infinity of 1/r^2 and 1/r^4) Done completely.
9) (Bullet and block mechanics one) Done completely... BUT at the last part, I had b and c in terms of R, m, M, and u. I've heard one person saying the question asked for b and c in terms of a, m, M and u, and multiple people saying it didn't ask for this. Eliminating R in place of a just involved substituting in R = 1/2 * mu^2/a; but I'll assume the question DID ask for b and c in terms of a, m, M and u.

Reply 147

Hauss

Q5 STEP II Solution

Spoiler

(edited 7 years ago)

Solution to Q12

Q12 Past 2.jpg377.1KB

Reply 150

Insight314

Original post by shamika

All I was doubting myself because Zacken said I didn't originall estimate 99 / 70 / 60 (I actually said 61 instead but whatever).

But I still think that is my best guess to date: 99 / 70 / 60. I'm also not sure comparing only to 2010 onwards is right either. Especially if Q1 and Q3 were easy then I think that is a reasonable guess.

ImageUploadedByStudent Room1466173913.405248.jpg

Reply 151

ln(sec(x))

Does anyone have access to a copy of the paper to see what question 9 wanted b and c in terms of, please?

Reply 152

Insight314

Original post by ln(sec(x))

Does anyone have access to a copy of the paper to see what question 9 wanted b and c in terms of, please?

In terms of m, M and R.

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Reply 153

gasfxekl

Original post by Insight314

There's such a thing called print screen...

Reply 154

shamika

Original post by Insight314

I thought private messages were meant to be private (but good to know that I wasn't losing my mind. I blame Zacken for the confusion this morning! :tongue:

)

Reply 155

Insight314

Original post by shamika

I thought private messages were meant to be private (but good to know that I wasn't losing my mind. I blame Zacken for the confusion this morning! :tongue:

)

Do you want me to remove it? Sorry about that, haha. I also forwarded it to Zacken and physicsmaths since they were also curious about the boundaries.

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Reply 156

shamika

Original post by Insight314

Do you want me to remove it? Sorry about that, haha. I also forwarded it to Zacken and physicsmaths since they were also curious about the boundaries.

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Nope, it's fine, I wish you were around this morning so I could avoid tying myself in knots. (I still stand by my estimates, but the obvious caveats apply. If I get some time I will try a few questions over the weekend to refine my view, but it's unlikely I'll have the time)

(edited 7 years ago)

Reply 157

YonRamires

Original post by Insight314

In terms of m, M and R.

no, in terms of m, M, and a, where a was the answer to the first part of the question

Reply 158

YonRamires

Hi, this is what I got, how many points/what grade should I expect?

2: complete, except I got a solution x=5 instead of x=4 on part (ii) (apparently i'm not good at adding and substracting one digit ints)
3: complete, except for checking double roots in the even case in the last part)
6: did parts (i), (ii), and (iii), not (iv)
7 (that was the question w/ four parts and integrals right?): only part (i)
9: complete, but in the last part I calculated the path of the bullet relative to the table (so b+c instead of b), so I got the value of b wrong
12: complete

Reply 159

Insight314