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OpenStudy (johnnydicamillo):
Solve for x
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OpenStudy (johnnydicamillo):
\[3^{4x} = 13 ^{-x +7}\] use base-10 logarithms
OpenStudy (zzr0ck3r):
take log of both sides
\(\log_{10}(3^{4x})=\log_{10}(13^{-x+7})\\4x\log_{10}(3)=(-x+7)\log_{10}(13)\)
OpenStudy (zzr0ck3r):
you with me?
OpenStudy (johnnydicamillo):
okay I am following
OpenStudy (zzr0ck3r):
can you solve for x?
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OpenStudy (zzr0ck3r):
distribute the log(13) on the right
OpenStudy (zzr0ck3r):
then add xlog(13) to both sides
OpenStudy (zzr0ck3r):
factor out the x on the left
divide to get x alone
OpenStudy (zzr0ck3r):
in that order:)
OpenStudy (johnnydicamillo):
um let me try.
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OpenStudy (zzr0ck3r):
k
OpenStudy (johnnydicamillo):
Okay, I am stuck on distributing logs.
OpenStudy (zzr0ck3r):
do it as you would a number
OpenStudy (zzr0ck3r):
(a+b)c = ac+bc
OpenStudy (zzr0ck3r):
here c = log(13)
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OpenStudy (zzr0ck3r):
\(\log_{10}(3^{4x})=\log_{10}(13^{-x+7})\\4x\log_{10}(3)=(-x+7)\log_{10}(13)\\4x\log_{10}(3)=-x\log_{10}(13)+7\log_{10}(13)\)
OpenStudy (zzr0ck3r):
\(\log_{10}(3^{4x})=\log_{10}(13^{-x+7})\\4x\log_{10}(3)=(-x+7)\log_{10}(13)\\4x\log_{10}(3)=-x\log_{10}(13)+7\log_{10}(13)\\4x\log_{10}(3)+x\log_{10}(13)=7\log_{10}(13)\\x(4\log_{10}(3)+\log_{10}(13))=7\log_{10}(13)\\x=\frac{7\log_{10}(13)}{4\log_{10}(3)+\log_{10}(13)}\)
OpenStudy (johnnydicamillo):
okay, let me see if I understand it.
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