Respuesta :

[tex]\mathrm{If\:}f\left(x\right)=g\left(x\right)\mathrm{,\:then\:}\ln \left(f\left(x\right)\right)=\ln \left(g\left(x\right)\right) \ \textgreater \ \ln \left(6^x\right)=\ln \left(21\right)[/tex]

[tex]\mathrm{Apply\:log\:rule}:\ \log _a\left(x^b\right)=b\cdot \log _a\left(x\right) \ \textgreater \ \ln \left(6^x\right)=x\ln \left(6\right) [/tex]

[tex]x\ln \left(6\right)=\ln \left(21\right) \ \textgreater \ \mathrm{Divide\:both\:sides\:by\:}\ln \left(6\right) \ \textgreater \ \frac{x\ln \left(6\right)}{\ln \left(6\right)}=\frac{\ln \left(21\right)}{\ln \left(6\right)} [/tex]

[tex]Therefore \: x=\frac{\ln \left(21\right)}{\ln \left(6\right)}[/tex]

In your case ln means [tex] \frac{log 21}{log 6} [/tex]
in your graphing calculator you have to press the button (2nd) then (catalog) which is the number (0). 
after that you press (ALPHA) (L) which iOS the button for the parenthesis (. ).  )
find LOG and then plug in the number you want.
repeat this until you get the equation you want.
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