toadytica305
How do you solve when you have logs on one side but not the other? (2 problems inside)
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toadytica305
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mathg8
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use the product rule log A + log B = log (AB)
toadytica305
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I tried that...
for Log x + log (x+15) = 2
I have (Log x)(log (x+15)) =2
i dont know what to do after
The answer is 5
saifoo.khan
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\[\lg x(x+15) = 2\]
RadEn
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convert 2 to log 100
AravindG
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log x+log (x+15)=log(x(x+15))!!
RadEn
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it just a hint, so that both sides have log's :)
toadytica305
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But how do you go from
log(x(x+15)=2.. to x=5?
I can't get that part
RadEn
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log(x(x+15))=2
log(x(x+15)=log100
cancel out the log, giving us :
x(x+15)=100 or
x^2+15x-100=0
solve for x by factorization or by complete square or by quadratic formula
RadEn
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got it ?
toadytica305
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Yes! Just solved it.. thank you!
RadEn
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yw
toadytica305
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I didn't think of doing log 100 to cancel the logs on both sides