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Math Help - Solve for x

  1. #1
    Junior Member
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    Solve for x

    i got √50 but its wrong

    Solve for :

    equals


    b) Solve for :
    equals
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  2. #2
    Senior Member
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    Hi wannous

    I also got x = √50 for the first question
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  3. #3
    Junior Member
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    can u help me with number 2 im not getting the right answer
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  4. #4
    Super Member
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     ln(x-7) + ln (x+7) = 0 \Leftrightarrow ln((x-7)(x+7)) = 0

     \Leftrightarrow e^{ln((x+7)(x-7))} = e^0 \Leftrightarrow (x+7)(x-7) = 1

     \Leftrightarrow x^2 = 50 \Leftrightarrow x = \sqrt{50}

    Other one:

    ln(x-4) - ln (2x-9) = 0 \Leftrightarrow ln( \frac{x-4}{2x-9}) = 0

    \Leftrightarrow e^{ln(\frac{x-4}{2x-9})} = e^0 \Leftrightarrow \frac{x-4}{2x-9} = 1

     \Leftrightarrow x-4 = 2x-9 \Leftrightarrow x = 5
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  5. #5
    Senior Member
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    Hi wannous

    Well, you can solve the first question so why can't you solve the second one? I got x = 5 for the second question using the same method to solve the first one
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