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log(5x+8)=3 - Logarithms

by Hailee
(Michigan)










































Solve the following Logarithmic equation for the variable x.

log(5x+8)=3

A logarithm reverses exponentiation.

Use the common logarithm base 10 in your solution.


Comments for log(5x+8)=3 - Logarithms

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Mar 09, 2012
log(5x+8)=3
by: Staff


Question:

by Hailee
(Michigan)


log(5x+8)=3


Answer:

log(5x + 8) = 3


log(5x + 8) = log(10³)

5x + 8 = 10³

5x + 8 = 1000

5x + 8 - 8 = 1000 - 8

5x + 0 = 992

5x = 992

5x/5 = 992/5

x*(5/5) = 992/5

x*(1) = 992/5

x = 992/5

x = 198.4


>>> the final answer is: x = 198.4


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Check the answer by substituting 198.4 for x in the original equation

log(5x + 8) = 3

log(5*198.4 + 8) = 3

log(992 + 8) = 3

log(1000) = 3

log(10³) = 3

3 = 3, OK → x = 198.4 is a VALID solution




Thanks for writing.

Staff
www.solving-math-problems.com



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