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IGCSE MATHS Doubts

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Fastal:

--- Quote from: ksitna on May 08, 2010, 05:31:41 pm ---uh im sorry
i dont really get it
how did u get -7?

--- End quote ---

i think its +9

@d!_†oX!©:

--- Quote from: ksitna on May 08, 2010, 05:31:41 pm ---uh im sorry
i dont really get it
how did u get -7?

--- End quote ---
see, first u substracct and then take the lcm
it is
+9-16 which is equal to -7
(x-3)/4  -  4/(x-3) = 0
then take lcm
so,
(x-3)(x-3) - 4*4 / 4x - 12 = 0
x2 -3x -3x +9 -16 / 4x-12 = 0
so the simplify and get
x2 - 6x -7 / 4x -12 = 0

Vin:

--- Quote from: ksitna on May 08, 2010, 05:31:41 pm ---uh im sorry
i dont really get it
how did u get -7?

--- End quote ---

(x-3) (x-3) - 16
------------------
   4x -12


x2 -6x + 9 - 16
------------------
   4x -12

x2 - 6x -7
------------------
   4x -12

Vin:

Ok guys i hav a doubt .. after a long time .. :P

ksitna:

--- Quote from: @d!_†oX!© on May 08, 2010, 05:39:35 pm ---see, first u substracct and then take the lcm
it is
+9-16 which is equal to -7
(x-3)/4  -  4/(x-3) = 0
then take lcm
so,
(x-3)(x-3) - 4*4 / 4x - 12 = 0
x2 -3x -3x +9 -16 / 4x-12 = 0
so the simplify and get
x2 - 6x -7 / 4x -12 = 0

--- End quote ---

the mark scheme says

x2-6x+25/4(x-3) :/

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