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Homework Help: Simplifying Equatons

  1. Nov 21, 2009 #1
    I have just been doing some algebra homework. The are just problems that I can't work out. I wonder if anyone can explain how to solve them?

    3x + (-3) = x + 199
    x = ?
    I know the answer is x = 101 but I haven't worked it out in the right way. I just did it by deduction which took ages. What is the right way to tackle this problem?

    I have the same problem with this one. I know that x = 25 but how do you work it out?

    -300 -(-4x) = + -8x
  2. jcsd
  3. Nov 21, 2009 #2


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    Homework Helper


    You're trying to solve for x so the ultimate goal here is to move all the x onto one side of the equation, and then simplify to isolate it, x=...

    [tex]-300-(-4x)=\pm 8x[/tex]

    Is that actually meant to be a [itex]\pm[/itex]? Because if so, the difficulty between the first and second equation is pretty significant. Unless of course I misread the first equation?

    Anyway, you can do this by mainly two ways:
    1) square both sides and solve the quadratic
    2) Take seperate cases, first use 8x and then -8x

    Oh and you do realize that [itex]-(-4x)=4x[/itex], right?
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