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anonymous

  • 5 years ago

Log2 x + 5 = 8 - log2 (x + 7)

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  1. anonymous
    • 5 years ago
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    add log2 (x + 7) to both sides, substract 5 from both sides, rewrite the log expression log2 x + log2 (x+7)as the log of a product. exponentiate both sides. get x

  2. anonymous
    • 5 years ago
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    u should get x = -1 and x = 8, but since x = -1 is outside the domain of the logarithm, reject it

  3. anonymous
    • 5 years ago
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    can u show me the workk but i think im doing it completely wrong...heres what i came up with...lol log2 x + log2 (x+7) = 3 log2 [x/(x+7)] 3 [x/(x+7)] = 6 x= 6(x+7)

  4. anonymous
    • 5 years ago
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    ok for step 2, log2 (x(x+7)) = 3, exponentiate both sides using 2, you will get x(x+7) = 8, then by collecting terms, x^2 - 7x - 8 = 0, solve for x

  5. anonymous
    • 5 years ago
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    u should get x = 8 and x = -1, but since the log is not defined at x = -1, you must reject this answer

  6. anonymous
    • 5 years ago
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    got it?

  7. anonymous
    • 5 years ago
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    ohhhh okayy so u get x=8 right??

  8. anonymous
    • 5 years ago
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    yup

  9. anonymous
    • 5 years ago
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    :)

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