Maths Problem

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  • Peew971 17 Feb 2013 18:34:13 4,703 posts
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    If anyone can help with that, thank you very much :)
    I know I need to find the trapezium's area but can't find the length of its sides without just guessing. Any brain around to help?

  • grey_matters 17 Feb 2013 18:50:22 3,676 posts
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    Let x be the longest side, y be the shorter one, and z the width.

    x + y = 30
    x + z = 24
    x = 2z (2 widths line up with the long side)

    So,
    x = 24 - z (re-arranging the second equation)

    which means:
    2z = 24 - z (because x = 2z)
    -> z = 8 (and x = 16, y = 14)

    You can probably do the rest yourself.

    Edited by grey_matters at 18:53:12 17-02-2013
  • Peew971 17 Feb 2013 19:11:54 4,703 posts
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    Great! I got those first 2 equations but didn't notice the long side being twice the width so I got stuck there.
    Thanks a lot :)
  • Deleted user 20 May 2013 21:21:26
    Help!

    http://i.imgur.com/0sIzcsW.png
    I'm useless at maths and I need to know how to answer these questions. It is the working I need. (not for me but I can't think of anyone else to run to!)

    Edited by mowgli at 21:21:45 20-05-2013
  • Shikasama 20 May 2013 21:22:28 6,634 posts
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    I didn't even know what a trapezium was.
  • Deleted user 20 May 2013 21:33:17
    Anyone?

    Wife needs to know for an exam in a couple of days and I'm fucking useless at maths :(
  • Chopsen 20 May 2013 21:34:49 15,731 posts
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  • Chopsen 20 May 2013 21:34:57 15,731 posts
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    Does that work?
  • Chopsen 20 May 2013 21:35:42 15,731 posts
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    Hah. Awesomes.
  • RichieTenenbaum 20 May 2013 21:39:31 2,181 posts
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    6) K=-3 (2 squared is 4. Multiply by 3 to get 12. -3 to get -12)

    7) (x + 2)^2 -3 (shifted left by 2, down by 3) (it's plus 2 as you need x to be -2 to get back to zero and make y -3)

    8) x = -1
    max at -1,1
  • Chopsen 20 May 2013 21:41:12 15,731 posts
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    Yeah. But mine's prettier.
  • RichieTenenbaum 20 May 2013 21:45:05 2,181 posts
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    It is.

    MUCH.
  • RichieTenenbaum 20 May 2013 21:45:58 2,181 posts
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    So, can we just type laTex into this forum?
  • X201 20 May 2013 21:48:15 15,148 posts
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    RichieTenenbaum wrote:
    So, can we just type laTex into this forum?
    You've never used the search function on here have you?
  • Chopsen 20 May 2013 21:48:22 15,731 posts
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    I went via this website, that coverts latex to a linkable gif:

    http://www.texify.com/links.php

    I was tempted to just paste some latex and see what happens, but I thought that might be overestimating poor old craigy
  • Chopsen 20 May 2013 21:48:41 15,731 posts
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    \[\sum\limits_{i = 1}^n {X_i^2} \]

    edit: no

    Edited by Chopsen at 21:48:52 20-05-2013
  • mrpon 20 May 2013 21:51:48 28,489 posts
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    RichieTenenbaum wrote:
    So, can we just type laTex into this forum?
    Afraid not, google: "mwnin laTex" for the syntax.

    Give yourself 5 or gig, you're worth it.

  • Deleted user 20 May 2013 21:51:56
    Genuine thanks, she says it helps a lot (looks like fucking alien talk to me). She doesn't know how you got the answer for 8 though?
  • Chopsen 20 May 2013 21:57:12 15,731 posts
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    at x = -1, the (x+1)^2 is equal to zero. All other values for x are going to be symmetrical around this. Raising something to the power of 2 "removes" the sign.

    So the axis of symmetry is x= -1.

    edit: why do I care?

    Edited by Chopsen at 22:07:32 20-05-2013
  • speedofthepuma 20 May 2013 22:01:47 13,268 posts
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    I used to know all this. How the hell does it stick in your stupid brain? You must be horribly deficient in some other way Chopsen.

    I've turned off all the avatars and crap, so don't expect me to be impressed by yours.

  • Chopsen 20 May 2013 22:04:06 15,731 posts
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    It's only because I am actually doing some maths part time at the moment. I generally can't remember anything from more than a couple of weeks ago unless it's written down otherwise.
  • RichieTenenbaum 20 May 2013 22:05:48 2,181 posts
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    You need to edit a sign there, Choppo
  • RichieTenenbaum 20 May 2013 22:09:46 2,181 posts
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    A better way to explain 8

    x^2 is symmetrical around 0

    (x+1)^2 must be symmetrical around -1. This makes the bracket 0.
    When x is -1.

    Then y = 1 + (-1+1)^2 = 1 + (0)^2 = 1
  • Deleted user 21 May 2013 08:15:49
    Thanks again, both. She was pulling her hair out and is now able to move on.
  • Alastair 21 May 2013 08:36:14 15,476 posts
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    I used to just about understand this sort of thing - did Maths A-level but failed it. :(

    I managed to work out 6 in my head. 7 I could have done on paper, 8 I would have struggled with.

    Not as nice as I used to be

  • robkilpatrick 21 May 2013 13:52:10 2 posts
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    It take so much time to help you out
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