Year 13 Maths Help Thread

Announcements Posted on
Four things that unis think matter more than league tables 08-12-2016
    Offline

    2
    ReputationRep:
    Hi, I was wondering if anyone could help me with this C3 Trigonometry question?Name:  image.jpeg
Views: 35
Size:  334.8 KB
    Online

    3
    ReputationRep:
    (Original post by Leah3852)
    Hi, I was wondering if anyone could help me with this C3 Trigonometry question?Name:  image.jpeg
Views: 35
Size:  334.8 KB
    Well, that's the same thing as saying x = \sin k for 0 < k < \frac{\pi}{2}, what's the range of sin k as k moves from 0 to pi/2. That is, what portion of the y-axis does sin k map to when you look at a graph of sin k?

    For b(i) you want to do \cos k = \cos (\arcsin x) and for b(ii) you want \tan(\arcsin x). Try drawing a right-angled triangle and finding the angle \arcsin x. then using cos (arcsin x) = adjacent/hypo, etc... let me know hoe you get on. Prove your attempt and I can see whether you're going along the right lines and what hints you need.
    Online

    3
    ReputationRep:
    How do I do this question?

    Find the value of \lambda for which \lambda x^2e^x is a particular integral for \frac{d^2y}{dx^2} -2 \frac{dy}{dx} + y =e^x
    Online

    3
    ReputationRep:
    (Original post by NotNotBatman)
    How do I do this question?

    Find the value of \lambda for which \lambda x^2e^x is a particular integral for \frac{d^2y}{dx^2} -2 \frac{dy}{dx} + y =e^x
    Find y' and y'' and then just plug it into the equation and compare coefficients.
    Online

    3
    ReputationRep:
    (Original post by B_9710)
    Find y' and y'' and then just plug it into the equation and compare coefficients.
    Thank you, it's the same as the other questions, just worded a little different.
    Offline

    1
    ReputationRep:
    Name:  IMG_2726.JPG
Views: 34
Size:  171.8 KBPart iii
    Offline

    3
    ReputationRep:
    (Original post by Coolsul98)
    Part iii
    What have you tried?
    • Thread Starter
    Online

    2
    ReputationRep:
    For y=(-1)^x, do we write f:\mathbb{R} \rightarrow \mathbb{Z} for the domain and codomain?
    Online

    3
    ReputationRep:
    (Original post by Palette)
    For y=(-1)^x, do we write f:\mathbb{R} \rightarrow \mathbb{Z} for the domain and codomain?
    That's not a function if you choose that domain.
    • Thread Starter
    Online

    2
    ReputationRep:
    (Original post by Zacken)
    That's not a function if you choose that domain.
    And of course, taking x=\frac{1}{2} means that y=(-1)^{\frac{1}{2}} isn't even a real number let alone an integer... another careless question on my part...

    Would f:\mathbb{Z} \rightarrow \mathbb{Z} make it a function?
    Online

    3
    ReputationRep:
    (Original post by Palette)
    Would f:\mathbb{Z} \rightarrow \mathbb{Z} make it a function?
    Yeah.
    Offline

    3
    ReputationRep:
    (Original post by k.russell)
    lol np, I am glad (and surprised) I could help out I am guessing you are studying some M units, how many have you done so far?
    Part way through M2 and I will be doing M3 as well, was originally going to do M3,4 and 5 but I'd rather focus on M3 and the rest of the further modules (FP1,2,3 M2,3 D1 and S2 I'll be doing)


    What about you?
    Offline

    2
    ReputationRep:
    (Original post by metrize)
    Part way through M2 and I will be doing M3 as well, was originally going to do M3,4 and 5 but I'd rather focus on M3 and the rest of the further modules (FP1,2,3 M2,3 D1 and S2 I'll be doing)


    What about you?
    I did M1 in my first year and got 70 ums (impressive, ik), I decided to stick with mechanics and try M2 and did a bit better, but still pretty bad lol (80 ums). I was actually really disappointing with M2 because it was like my lowest A2 exam by quite a way in any subject. I also thought that I had only got one problem wrong from the model answers, so I think I possibly lost marks for working out??
    That would be my biggest tip for mechanics, make sure your diagrams are very clear - as like most of the M2 marks are for the set up of the initial equations and the diagrams are part of that.
    I never really got on particularly well with mechanics in all honesty. It took me a while to learn and it doesn't go that well with my other subjects and is unlikely to be useful to me in the future! But I'm glad I did the little bit I did
    Offline

    2
    ReputationRep:
    Hey, I want to see what someone else gets because im confused as to why my answer is wrong.

    By what percentage is the heaviest girl heavier than the lightest girl (to the nearest whole number)?
    if the heaviest = 143 lb and the lightest = 111lb.
    What answer did you get?


    I got 22 %
    Spoiler:
    Show
    apparently it's 29% but idk how?

    I did 143-111 divided by 143 x 100 ?
    Online

    3
    ReputationRep:
    (Original post by medhelp)
    Hey, I want to see what someone else gets because im confused as to why my answer is wrong.

    By what percentage is the heaviest girl heavier than the lightest girl (to the nearest whole number)?
    if the heaviest = 143 lb and the lightest = 111lb.
    What answer did you get?


    I got 22 %
    Spoiler:
    Show
    apparently it's 29% but idk how?

    I did 143-111 divided by 143 x 100 ?
    (143-111)/111 * 100 because it's asking heavier than the lightest girl, so your starting reference is the lightest girl. Hence why you divide by 111.
    Offline

    3
    ReputationRep:
    (Original post by k.russell)
    I did M1 in my first year and got 70 ums (impressive, ik), I decided to stick with mechanics and try M2 and did a bit better, but still pretty bad lol (80 ums). I was actually really disappointing with M2 because it was like my lowest A2 exam by quite a way in any subject. I also thought that I had only got one problem wrong from the model answers, so I think I possibly lost marks for working out??
    That would be my biggest tip for mechanics, make sure your diagrams are very clear - as like most of the M2 marks are for the set up of the initial equations and the diagrams are part of that.
    I never really got on particularly well with mechanics in all honesty. It took me a while to learn and it doesn't go that well with my other subjects and is unlikely to be useful to me in the future! But I'm glad I did the little bit I did
    Ah I see, yeah mechanics is pretty tricky, diagrams really do help. I got 85 UMS in M1 that I did, even though I thought it would be close to 100 but grade boundaries were pretty high this year compared to usual so oh well :P
    Offline

    2
    ReputationRep:
    Name:  IMG_0377[1].jpg
Views: 18
Size:  501.8 KB
    can someone help me with this complex numbers problem? it's under the subtopic of polar notation.
    The main bit I don't really understand is that AB^2 = 39. For me, as A & B both contain i, AB^2 should have i^3 in it so can't = 36. I don't understand it lol
    Zacken maybe?
    Online

    3
    ReputationRep:
    (Original post by k.russell)
    can someone help me with this complex numbers problem? it's under the subtopic of polar notation.
    The main bit I don't really understand is that AB^2 = 39. For me, as A & B both contain i, AB^2 should have i^3 in it so can't = 36. I don't understand it lol
    Zacken maybe?
    I think the question is just using excessively bad notation and means that the distance between A and B^2 is 39. Not the complex numbers A multiplied by B^2 is 39.
    Offline

    2
    ReputationRep:
    (Original post by k.russell)
    Name:  IMG_0377[1].jpg
Views: 18
Size:  501.8 KB
    can someone help me with this complex numbers problem? it's under the subtopic of polar notation.
    The main bit I don't really understand is that AB^2 = 39. For me, as A & B both contain i, AB^2 should have i^3 in it so can't = 36. I don't understand it lol
    Zacken maybe?
    it means the modulus is sqrt39
    Offline

    2
    ReputationRep:
    (Original post by Zacken)
    I think the question is just using excessively bad notation and means that the distance between A and B^2 is 39. Not the complex numbers A multiplied by B^2 is 39.
    rigghtt.. that does make more sense I'll have another crack at it and report back, I think you're right though - that's unbelievably badly posed though thanks for your help
 
 
 
Write a reply… Reply
Submit reply

Register

Thanks for posting! You just need to create an account in order to submit the post
  1. this can't be left blank
    that username has been taken, please choose another Forgotten your password?
  2. this can't be left blank
    this email is already registered. Forgotten your password?
  3. this can't be left blank

    6 characters or longer with both numbers and letters is safer

  4. this can't be left empty
    your full birthday is required
  1. Oops, you need to agree to our Ts&Cs to register
  2. Slide to join now Processing…

Updated: December 9, 2016
TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

Poll
Do you think you'll achieve your predicted A Level grades?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read here first

Equations

How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups
Study resources

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.