Maths help

• StarPuppy

  3 Sep 05, 21:50

  anyone know how to solve this type of question?
  [ 2x(square)-5x+3 ]
  
  without the help of a calculator
  
  what is the fastest way?
  
  Thanks
  
  ~+StarPuppy+~
• polarsnake

  3 Sep 05, 21:52

  Originally posted by StarPuppy:
  anyone know how to solve this [b]type of question?
  [ 2a(square)-7a+13a ]
  
  without the help of a calculator
  
  what is the fastest way?
  
  Thanks
  
  ~+StarPuppy+~[/b]

  paiseh, i wrong... but you never put =0 at the back what...
  
• hopy

  3 Sep 05, 21:52

  Originally posted by StarPuppy:
  anyone know how to solve this [b]type of question?
  [ 2a(square)-7a+13a ]
  
  without the help of a calculator
  
  what is the fastest way?
  
  Thanks
  
  ~+StarPuppy+~[/b]

  2a^2-7a+13a=0
  
  2a^2+6a=0
  
  a(2a+6)=0
  
  a = 0
  
  OR
  
  a = -3
  
  dunno if im correct or not but shld be like tt lah
• the Bear

  3 Sep 05, 21:53

  2a^2 -7a +13a
  
  = 2a^2 +6a
  
  = 2a ( a + 3 )
  
  if it's a quadratic equation, just factorise it.. if not, just go with the formula...
  
  

  Originally posted by StarPuppy:
  anyone know how to solve this [b]type of question?
  [ 2a(square)-7a+13a ]
  
  without the help of a calculator
  
  what is the fastest way?
  
  Thanks
  
  ~+StarPuppy+~[/b]

• poon cho tang

  3 Sep 05, 21:54

  can solve algebraic problems on a calculator?
• StarPuppy

  3 Sep 05, 21:56

  oops
  
  my bad ppl
  
  its err...
  [ 2x(square)-5x+3 ]
• rainee

  3 Sep 05, 21:57

  Originally posted by poon cho tang:

  can solve algebraic problems on a calculator?

  can...if u use the right one
• rainee

  3 Sep 05, 21:59

  Originally posted by StarPuppy:

  oops
  
  my bad ppl
  
  its err...
  [ 2x(square)-5x+3 ]

  Use the the quadratic formula
  
  (b+/- square root(b^2 + 4ac))/2a
• poon cho tang

  3 Sep 05, 21:59

  Originally posted by rainee:

  can...if u use the right one

  wow...i never had that luxury
• rainee

  3 Sep 05, 22:00

  Originally posted by poon cho tang:

  wow...i never had that luxury

  it is also a very expensive one
• 798

  3 Sep 05, 22:01

  Originally posted by StarPuppy:

  oops
  
  my bad ppl
  
  its err...
  [ 2x(square)-5x+3 ]

  Cross Multiply!
  
  2x 1
  x -3
  
  2x^2 - 5x + 3 = (x-3)(2x+1)
• StarPuppy

  3 Sep 05, 22:02

  Originally posted by rainee:

  Use the the quadratic formula
  
  (b+/- square root(b^2 + 4ac))/2a

  but sometimes the square root will result in a decimal point
• StarPuppy

  3 Sep 05, 22:10

  how to do a quick cross multi...it always take me hours to do one cross
• rainee

  3 Sep 05, 22:14

  Originally posted by StarPuppy:

  how to do a quick cross multi...it always take me hours to do one cross

  Eh...it takes practice...but after a while you can start doing it in your head
• hisoka

  3 Sep 05, 22:14

  Originally posted by StarPuppy:

  how to do a quick cross multi...it always take me hours to do one cross

  erm i always just do it in my mind one ust ry combi nations of both multiples andtry and find one that fits
• monkeybusiness

  3 Sep 05, 22:15

  Originally posted by rainee:

  Eh...it takes practice...but after a while you can start doing it in your head

  x2
  maths is all bout practising
• rainee

  3 Sep 05, 22:16

  Originally posted by monkeybusiness:

  x2
  maths is all bout practising

  I must have done thousands of questions when I prepared for my high school math exam last time
• 798

  3 Sep 05, 22:18

  Originally posted by StarPuppy:

  how to do a quick cross multi...it always take me hours to do one cross

  it takes practice plus good eyesight.
  
  last time i realised that finally result is look at it horizonal.
  
  remember this well too:
  1 = 1 x 1
  2 = 1 x 2
  3 = 1 x 3
  4 = 1 x 4 or 2 x 2
  5 = 1 x 5 or 2 x 2.5
  
  you can do it one
• StarPuppy

  3 Sep 05, 22:21

  is quad equation better or cross multi better?
• monkeybusiness

  3 Sep 05, 22:21

  Originally posted by rainee:

  I must have done thousands of questions when I prepared for my high school math exam last time

  me too
• monkeybusiness

  3 Sep 05, 22:22

  Originally posted by StarPuppy:

  is quad equation better or cross multi better?

  depend on individuals and whether the qn state to use which one
• StarPuppy

  3 Sep 05, 22:23

  but quad equation...what happens if the number cannot square root...does it mean that quad equation is not foolproof? or is the question wrong?
• rainee

  3 Sep 05, 22:24

  Originally posted by StarPuppy:

  but quad equation...what happens if the number cannot square root...does it mean that quad equation is not foolproof? or is the question wrong?

  No...sometimes you will get complex numbers...meaning you get negative numbers inside your square root, that means you answer wud be in complex number...
• 798

  3 Sep 05, 22:25

  Originally posted by StarPuppy:

  is quad equation better or cross multi better?

  cross 1st. cannot factorise directly, try quadratric.
  
  do you know how to do expansion?
• hisoka

  3 Sep 05, 22:25

  Originally posted by monkeybusiness:

  depend on individuals and whether the qn state to use which one

  erm i guess cross is better lah. using simultaneous eqn is like doing 2 questions to get the answer to one question.
  
  jsut try and do more and try to do in your head after you have got the hang of crossing