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Algebra

Discussion in 'General Discussion' started by speedyj, 6 Jun 2010.

  1. speedyj

    Hitman

    Joined: 19 Mar 2006

    Posts: 635

    Location: Suffolk

    a=2, b=-4, c=-3


    a³ - 2b - 4c²

    Can someone solve this please?
     
  2. SideWinder

    Consigliere

    Joined: 12 Jun 2004

    Posts: 149,513

    Location: NW5

    (2x3) - (2x-4) - (4x-3x2).

    I think...i got a C for Maths GCSE. :p
     
  3. Ahleckz

    Capodecina

    Joined: 7 Nov 2009

    Posts: 18,288

    Location: Glasgow

    Edited so noone knows I was *ahem* right *ahem*
     
    Last edited: 6 Jun 2010
  4. Fegruson

    Wise Guy

    Joined: 6 Jan 2009

    Posts: 1,049

    Location: Derby

  5. SideWinder

    Consigliere

    Joined: 12 Jun 2004

    Posts: 149,513

    Location: NW5

    I wasn't going to do his homework for him...! :p
     
  6. Fegruson

    Wise Guy

    Joined: 6 Jan 2009

    Posts: 1,049

    Location: Derby

    :p

    Not even sure it's correct tbh! :D
     
  7. fidget

    Hitman

    Joined: 22 Apr 2010

    Posts: 630

    Location: NW England

  8. Lydzor

    Hitman

    Joined: 19 Apr 2007

    Posts: 781

    I got -20 also. :)
     
  9. Cosimo

    Man of Honour

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    Location: Londinium

  10. icysniper

    Hitman

    Joined: 4 Jun 2009

    Posts: 882

    Location: South Wales

    hmm i get 124:confused:

    8 - -8 - -108

    = 8+8+108 = 124:confused:

    EDIT: my bad lemme work it out again

    yeh got -20, for some reason i thought it was cubed for C, wtf was i thinking?
     
  11. DB_SamX

    Sgarrista

    Joined: 17 Feb 2006

    Posts: 8,303

    Location: Winchester

    Would be an F really here.;)
     
  12. fidget

    Hitman

    Joined: 22 Apr 2010

    Posts: 630

    Location: NW England

  13. Hamster

    Soldato

    Joined: 25 Oct 2002

    Posts: 5,650

    Location: location: location

    -20. This is very basic year 8 maths.
     
  14. Lydzor

    Hitman

    Joined: 19 Apr 2007

    Posts: 781

    I'm guessing people are misunderstanding powers and how to calculate minus numbers.
     
  15. SideWinder

    Consigliere

    Joined: 12 Jun 2004

    Posts: 149,513

    Location: NW5

    ...was my method correct by the way?
     
  16. speedyj

    Hitman

    Joined: 19 Mar 2006

    Posts: 635

    Location: Suffolk

    a=2, b=-4, c=-3

    a³ - 2b - 4c²

    As before, start with the "Not thinking" line:
    2³ -8x(-4) -4x(-3)²

    now sort out the numbers:
    8 not 6!!!! It's 2x2x2 = 4x2 = 8
    + 32 minus times a minus is a plus
    - 36 do it carefully, (-3)² = +9, -4x9 = -36
    = 4

    This is the explanation on a website my daughter has been pointed to by her teacher.
     
  17. Skillmister

    Capodecina

    Joined: 3 Oct 2009

    Posts: 19,786

    Location: Wales

    (2x2x2) - (-4x2) - (4x(-3x-3))
    =
    8 - -8 - (4x9)
    =
    16--36
    =
    -20




    edit: its -20
     
  18. TheCenturion

    Capodecina

    Joined: 18 Mar 2008

    Posts: 12,755

    Come on people this isn't hard at all!

    I'll even put it into words!

    2 cubed is 8

    2 times -4 is -8

    -3 squared is 9, and 9 x 4 is 36

    8 take away negative 8 is 16. 16 take away 36 is -20

    That was simples.
     
  19. Lightnix

    Soldato

    Joined: 11 Sep 2007

    Posts: 5,362

    Location: from the internet

    Where'd you get -8x(-4) from then? :confused:
     
  20. speedyj

    Hitman

    Joined: 19 Mar 2006

    Posts: 635

    Location: Suffolk

    Its not my expression, I don't understand where that comes from either, it is on the website that my daughter was pointed to.

    It looks wrong to me also.