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Log_{7 }(5 - 3x)
Find the derivative​

1 Answer

4 votes

Let y be the expression you want to differentiate:


y=\log_7(5-3x) \implies 7^y=5-3x

Now,


7^y=e^(\ln(7^y))=e^(y\ln(7))

Use the chain rule to differentiate both sides with respect to x :


\ln(7)e^(y\ln(7))(\mathrm dy)/(\mathrm dx)=-3

Solve for dy/dx :


\ln(7)7^y(\mathrm dy)/(\mathrm dx)=-3


(\mathrm dy)/(\mathrm dx)=-\frac3{\ln(7)7^y}


(\mathrm dy)/(\mathrm dx)=\boxed{-\frac3{\ln(7)(5-3x)}}

User Awiebe
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