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anyone good at emaths?

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  • pandemona
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    13 posts since Apr '06
    • 02 Oct `07, 2:55PM

      as above and willing to trade msn cause i have quite alot question to ask...thanks PM me please
      and im not a clone...lol just needed some help

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    Darkness_hacker99
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    31,746 posts since Jun '05
  • wishboy
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    1,269 posts since Aug '05
    • 02 Oct `07, 3:20PM

      mi
      however only up to sec 3 Smile
      although i must say i screwed my emaths paper 2 today Laughing the teacher trying to kill ppl, set until so difficult

      Edited by wishboy 02 Oct `07, 3:21PM
  • HyuugaNeji
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    1,648 posts since Jun '05
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    eagle
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  • newcomer
    ALL YOUR BASES ARE BELONG TO ME
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    6,683 posts since Apr '05
  • pandemona
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    13 posts since Apr '06
  • cApitaland
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    4,417 posts since Sep '05
    • 02 Oct `07, 7:44PM

      post your questions here.

      there are more than enough qualified people here from both poly and jc.

      sadly i got only a2.

  • euc
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    656 posts since Aug '07
  • pandemona
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    13 posts since Apr '06
  • lpx88
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    6,985 posts since Jun '05
    • 02 Oct `07, 7:55PM
      Originally posted by pandemona:
      Factorisation
      a) 4x²-12x+9=0
      b) 2x²=7x

      a)4x²-12x+9 =0
      = (2x-3)(2x-3) =0
      2x-3=0
      2x=3
      x=1.5

      b)2x²=7x
      2x²-7x=0
      x(2x-7) =0
      x =0 or 2x-7 =0
      2x=7
      x=3.5

      x=0 or 3.5

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    eagle
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  • euc
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  • CoolMyth
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  • dbowie
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    4,041 posts since Mar '07
    • 02 Oct `07, 8:49PM
      Originally posted by pandemona:
      Factorisation
      a) 4x²-12x+9=0
      b) 2x²=7x

      a)(2x-3)(2x-3)=0
      x=3/2

      b)2x^2-7x=0
      x(2x-7)=0
      x=0 or 3.5

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    eagle
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  • popikachu
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  • pandemona
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    13 posts since Apr '06
  • unclebutcher
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    2,819 posts since Oct '06
  • pandemona
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    13 posts since Apr '06
    • 03 Oct `07, 2:40PM

      can someone teach me how to do completing the square?

      example: 2x²+7x-3=0

      and : 2x=5 - 1/x

  • Moderator
    eagle
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    17,965 posts since Aug '01
    • 03 Oct `07, 5:04PM
      Originally posted by pandemona:
      can someone teach me how to do completing the square?

      example: 2x²+7x-3=0

      and : 2x=5 - 1/x

      2x²+7x-3=0
      2(x²+3.5x) -3 =0
      2(x²+3.5x+[3.5/2]²) - 2[3.5/2]² -3 = 0
      2(x+3.5/2)² - 9.125 = 0

      Usually as a quick way of checking such questions whether you did correctly, what you do is to sub in values for 1 side to check.

      ie
      if x=0, 2x²+7x-3 = -3
      if x=0, 2(x+3.5/2)² - 9.125 = -3

      u can try for x=1 to further confirm
      If same, then confirm correct. No need to recheck question at all. Save your time for other stuff

      Part 2
      multiply x throughout
      2x² = 5x - 1
      2x² - 5x + 1 = 0

      From here try yourself first following my above steps

  • HyuugaNeji
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    1,648 posts since Jun '05
    • 03 Oct `07, 5:43PM

      2(x+3.5/2)² - 9.125 = 0

      2(x+3.5/2)²=9.125
      (x+3.5/2)²=4.5625
      (x+3.5/2)=+2.316 or -2.316
      x=0.386 or -4.066

  • Moderator
    eagle
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    17,965 posts since Aug '01
    • 03 Oct `07, 5:45PM
      Originally posted by HyuugaNeji:
      2(x+3.5/2)²=9.125
      (x+3.5/2)²=4.5625
      (x+3.5/2)=+2.316 or -2.316
      x=0.386 or -4.066

      Mad Mad Mad
      I let him try first one leh
      Mad Mad Mad

  • pandemona
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    13 posts since Apr '06
    • 03 Oct `07, 8:39PM

      i dont quite understand how u get this part
      2(x²+3.5x+[3.5/2]²) - 2[3.5/2]² -3 = 0

      how u get - 2[3.5/2]²

  • Moderator
    eagle
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    17,965 posts since Aug '01
    • 03 Oct `07, 8:40PM
      Originally posted by pandemona:
      i dont quite understand how u get this part
      2(x²+3.5x+[3.5/2]²) - 2[3.5/2]² -3 = 0

      how u get - 2[3.5/2]²

      inside I add
      so outside I subtract

      so in the end add zero, which does not affect the equation at all

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