SOLUTION: Solve for x. log3 (x+4) x log3 (x-4) = 0 Check the validity of each solution in the original equation.

Question 437731: Solve for x.
log3 (x+4) x log3 (x-4) = 0
Check the validity of each solution in the original equation.
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
log3 (x+4) x log3 (x-4) = 0
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[log(x+4)/log(3)] = 0
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Multiply thru by (log(3))^2 to get:
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log(x+4)*log(x-4) = 0
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Either log(x+4) = 0 or log(x-4) = 0
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If log(x+4) = 0, x+4= 1, so x = -3
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If log(x-4) = 0, x-4= 1, so x = 5
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Checking:
x = -3 ?
log3(-3+4)*log(-3-4) = 0
Wrong; you cannot have log(-7)
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x = 5
log3(5+4)*log(5-4) = 0
log3(9)*log(1) = 0
2*0 = 0
Good
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Conclusion: x = 5
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cheers,
Stan H.
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Cheers,
Stan H.
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