SOLUTION: Please help to Solve for x: Log (x+3)+Log (x-2)=Log14 (all 3 Logs are to the base 10)
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Question 1058789
:
Please help to Solve for x:
Log (x+3)+Log (x-2)=Log14
(all 3 Logs are to the base 10)
Found 2 solutions by
solve_for_x, Alan3354
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Answer by
solve_for_x(190)
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Using the logarithm law log(a) + log(b) = log(ab) gives:
log((x+3)(x-2)) = log(14)
Taking the antilog of both sides gives:
(x + 3)(x - 2) = 14
x^2 + x - 6 = 14
x^2 + x - 20 = 0
(x +5)(x - 4) = 0
x = -5, x = 4
Since the log function is not defined for values less than 0, the
x = -5 solution is discarded because -5 + 3 = -2 and -5 - 2 = -7.
The only solution that works is x = 4.
Answer by
Alan3354(69443)
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Log (x+3)+Log (x-2)=Log14
Log((x+3)*(x-2)) = Log14
Log((x+3)*(x-2)) = Log(14)
x^2 + x - 6 = 14
x^2 + x - 20 = 0
(x+5)*(x-4) = 0
x = -5 ** rejected, gives log of a negative value.
x = 4