- #1
nvez
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Homework Statement
Resolve the following equation:
log2 x + log2 [(x-3)/5)] = 3
Homework Equations
Logarithmic laws:
logc m + logc n = logc mn
The Attempt at a Solution
Restriction:
(x-3)/5 > 0
x-3 > 0
x > 3
Resolution:
log2 x + log2 [(x-3)/5)] = 3
log2 x[(x-3)/5)] = 3
log2 [(x2 - 3x)/5x] = 3
23 = (x2 - 3x)/5x
8 = (x2 - 3x)/5x
8(5x) = x2 - 3x
40x = x2 - 3x
40x + 3x = x2
43x = x2
43 = x2 / x
43 = x
My answer book says the answer is 8 however I don't seem to get to that after numerous attempts.
Thank you in advanced.
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