math problem

• jiaweiwei87

  19 Jul 07, 11:07

  Solve each pair of equations:
  
  1) 5x + 2y = 11 and x + y = 4
  
  2) 2p + 5q = 15 and 6p + 15q = -29
  
  3) 3a + b = 4 and 6a + 2b = 8
  
  Show Work Please. Thank You
• stellazio

  19 Jul 07, 11:10

  isn't this simultaneous equations?
  
  are u really born in 1987?
• hisoka

  19 Jul 07, 11:13

  question 2 is erm you type wrong or the question got problem? LHS are the same de......
• jiaweiwei87

  19 Jul 07, 11:16

  Originally posted by stellazio:

  isn't this simultaneous equations?
  
  are u really born in 1987?

  just help my bro asking
• the_unknown

  19 Jul 07, 11:20

  1) 5x + 2y = 11 and x + y = 4
  from eqn 2 => x = 4 - y.
  sub into eqn 1 => 5(4-y) + 2y = 11
  => 20 - 5y + 2y = 11
  => 9 = 3y
  => y = 3
  => x = 1
  
  2) 2p + 5q = 15 and 6p + 15q = -29
  no solution
  
  3) 3a + b = 4 and 6a + 2b = 8
  a= any element of R (real nos)
  b= 4 - 3a
• ndmmxiaomayi

  19 Jul 07, 11:34

  1) 5x + 2y = 11 - (1)
  x + y = 4 - (2)
  From (2),
  x = 4 - y - (3)
  Substitute (3) into (1),
  5(4 - y) + 2y = 11
  20 - 5y + 2y = 11
  20 - 3y = 11
  20 - 11 = 3y
  9 = 3y
  3 = y
  Substitute y = 3 into (2),
  x + 3 = 4
  x = 4 - 3
  = 1
  
  Therefore, x = 1, y = 3
  
  OR
  
  5x + 2y = 11 - (1)
  x + y = 4 - (2)
  (2) X 2: 2x + 2y = 8 - (3)
  (1) - (3): 3x = 3
  x = 1
  Substitute x = 1 into (2),
  1 + y = 4
  y = 4 - 1
  = 3
  
  Therefore, x = 1, y = 3
  
  2) LHS = RHS. Unless you are at higher level, this is not possible.
  
  3) Same as question 2.
• jiaweiwei87

  19 Jul 07, 13:20

  use either combination or substitution (i.e., either 1] add the two sides of the two equations together, or 2] solve one equation for one variable, and substitute that into the other equation)......i just knew it thank!!
• CoolMyth

  19 Jul 07, 13:30

  No need me.
• ndmmxiaomayi

  19 Jul 07, 20:47

  Originally posted by jiaweiwei87:

  use either combination or substitution (i.e., either 1] add the two sides of the two equations together, or 2] solve one equation for one variable, and substitute that into the other equation)......i just knew it thank!!

  I don't think you know.
  
  You sure you understand?
• unclebutcher

  19 Jul 07, 20:52

  can use reduced row echelon formation using GC too.
• eagle

  19 Jul 07, 21:02

  Originally posted by unclebutcher:

  can use reduced row echelon formation using GC too.

  aiyah...
  
  my power calculator can solve up to 3 variables simultaneous equations. Just key in the values only =D
• unclebutcher

  19 Jul 07, 22:53

  Originally posted by eagle:

  aiyah...
  
  my power calculator can solve up to 3 variables simultaneous equations. Just key in the values only =D

  mine also can! casio 911Z something
  
  but i got even more power calculator....texas instruments one...dun pray pray
• eagle

  19 Jul 07, 23:06

  Originally posted by unclebutcher:

  mine also can! casio 911Z something
  
  but i got even more power calculator....texas instruments one...dun pray pray

  yours not allowed in uni!
  Ha!
• ^tamago^

  19 Jul 07, 23:13

  2) not possible
  3) LHS=RHS.
• unclebutcher

  20 Jul 07, 15:50

  Originally posted by eagle:

  yours not allowed in uni!
  Ha!

  haha which one? the casio is o level one
• eagle

  20 Jul 07, 19:25

  Originally posted by unclebutcher:

  haha which one? the casio is o level one

  texas instrument
  
  mine is casio fx-570ms. Not allowed in Os and As, but allowed in uni
• Runawaylove

  19 Aug 07, 01:02

  Haha. Actually can bring in one lor. They say the teachers wont check the model of the calculator de. But when you write the calculator model down, just "cheat". Memorise a "legal" calculator first, lol. But no integrity la. Haha. My friend did it man. Pro.
  
  Anw, new to this forum. First post (:
  
• Darkness_hacker99

  19 Aug 07, 01:03

  Originally posted by Runawaylove:

  Haha. Actually can bring in one lor. They say the teachers wont check the model of the calculator de. But when you write the calculator model down, just "cheat". Memorise a "legal" calculator first, lol. But no integrity la. Haha. My friend did it man. Pro.
  
  Anw, new to this forum. First post (:
  

  Welcome to sgForums, hope you'll enjoy your stay.
• hiphop2009

  19 Aug 07, 01:05

  Originally posted by Darkness_hacker99:

  Welcome to sgForums, hope you'll enjoy your stay.

  n so glad tat he made his first post in homework forum
• unclebutcher

  19 Aug 07, 01:06

  Originally posted by Runawaylove:

  Haha. Actually can bring in one lor. They say the teachers wont check the model of the calculator de. But when you write the calculator model down, just "cheat". Memorise a "legal" calculator first, lol. But no integrity la. Haha. My friend did it man. Pro.
  
  Anw, new to this forum. First post (:
  

  ya they wont check. but if its o levels and you bring in some chunky calc of cuz they suspect something's fishy
• eagle

  19 Aug 07, 01:06

  Originally posted by Runawaylove:

  Haha. Actually can bring in one lor. They say the teachers wont check the model of the calculator de. But when you write the calculator model down, just "cheat". Memorise a "legal" calculator first, lol. But no integrity la. Haha. My friend did it man. Pro.
  
  Anw, new to this forum. First post (:
  

  me brought 2 calculators in exam... One is the allowed version... So I didn't cheat when writing down the model number
• Runawaylove

  19 Aug 07, 22:57

  Originally posted by hiphop2009:

  n so glad tat he made his first post in homework forum

  Im a "her"! D: < Got guys nick so gay one meh. HAHA Hahahaha. Anw, thanks for the welcome, mods!