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Isolating the variable

  1. Oct 20, 2004 #1
    k i am in grade 9 have a terrible math teacher and i need help with this stuff here is an example
    -5r + 6 =8
    so can u please explain to me how to exactly do this stuff.
  2. jcsd
  3. Oct 20, 2004 #2


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    [tex] -5r + 6 =8 [/tex]

    Well whatever you do on your equation you must do it on both sides of it.
    to get r alone we could substract 6 from both sides so

    [tex] -5r + 6 -6 =8 - 6[/tex]

    [tex] -5r = 2[/tex]

    Now could divide by -5 both sides.

    [tex] r = \frac{2}{-5}[/tex]

    there you go, was i clear enough?
  4. Oct 20, 2004 #3
    One word of extra advice from someone who almost failed algebra: Make sure you get it the first time, but if not, ask your instructor, or even us, for clarification. But I see that you have done that already. Good luck!
  5. Oct 21, 2004 #4


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    dumb dumb:
    Here's a way you ought to think about an equation:
    Think of it as an old-fashioned weight which has two bowls attached to a rod with a fulcrum in the middle, and that that weight must stay in BALANCE all the time.
    Such a weight would tip to one side if more weight was added to the bowl on that side than the other.
    Hence, the only operations you're allowed to do is:
    1.Add/subtract the same amount on both sides
    (This would keep the weight in balance)
    2.Multiply/divide with the same factor on both sides
    This would also keep the weight in balance.
    3. Substitute an equal amount to what's in ONE of the bowls:
    For example, if you have:
    2+3=4x+4, then you can, of course write this as 5=4x+4, since 2+3=5
    Last edited: Oct 21, 2004
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