Question 462323: solve log(2x+5)=3
Answer by math-vortex(648)   (Show Source):
You can put this solution on YOUR website! Solve log(2x+5) = 3
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There are several ways to solve logarithm equations. Here's one method I like.
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When no base is indicated in the logarithm, base 10 is implied. Recall that the logarithm function is the inverse of the exponential function. We use this idea to rewrite the log problem as an exponent problem.
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The answer to a log problem is always an exponent. In this case, the exponent is 3. Rewriting as an exponent problem, we have
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log(2x+5) = 3
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2x + 5 = 10^3
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Now solve for x.
2x + 5 = 1000
2x = 1000 - 5
2x = 995
x = 497.5
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It's always a good idea to check your answer using the original equation.
log(2x+5) = 3
log(2(497.5)+5) = 3
log(995 + 5) = 3
log(1000) = 3
3 = 3 (true!)
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Hope this helps!
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Ms.Figgy
math.in.the.vortex
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