You can show this using the calc on the forum. That way we can see straight away if it is correct :)
$${{\mathtt{4}}}^{\left({\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{x}}\right)}{\mathtt{\,\small\textbf+\,}}{\mathtt{1}} = {\mathtt{8}} \Rightarrow \left\{ \begin{array}{l}{\mathtt{x}} = {\frac{{ln}{\left({\mathtt{\,-\,}}{\sqrt{{\mathtt{7}}}}\right)}}{{ln}{\left({\mathtt{4}}\right)}}}\\
{\mathtt{x}} = {\frac{{ln}{\left({\mathtt{7}}\right)}}{\left({\mathtt{2}}{\mathtt{\,\times\,}}{ln}{\left({\mathtt{4}}\right)}\right)}}\\
\end{array} \right\}$$
$${\frac{{ln}{\left({\mathtt{7}}\right)}}{\left({\mathtt{2}}{\mathtt{\,\times\,}}{ln}{\left({\mathtt{4}}\right)}\right)}} = {\mathtt{0.701\: \!838\: \!730\: \!514\: \!401}}$$
Thanks EinsteinJr
The web2 calc will calculate log base 4 but most will not.
This is a more usual approach
42x=7
log42x=log7
2x*log4=log7
2x=log7/log4
x=log7/(2*log4)
the log can be any base so long as they are both the same base .
So x≈0.701838730514401 (this isn't the exact value, the number being irrationnal)
You can show this using the calc on the forum. That way we can see straight away if it is correct :)
$${{\mathtt{4}}}^{\left({\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{x}}\right)}{\mathtt{\,\small\textbf+\,}}{\mathtt{1}} = {\mathtt{8}} \Rightarrow \left\{ \begin{array}{l}{\mathtt{x}} = {\frac{{ln}{\left({\mathtt{\,-\,}}{\sqrt{{\mathtt{7}}}}\right)}}{{ln}{\left({\mathtt{4}}\right)}}}\\
{\mathtt{x}} = {\frac{{ln}{\left({\mathtt{7}}\right)}}{\left({\mathtt{2}}{\mathtt{\,\times\,}}{ln}{\left({\mathtt{4}}\right)}\right)}}\\
\end{array} \right\}$$
$${\frac{{ln}{\left({\mathtt{7}}\right)}}{\left({\mathtt{2}}{\mathtt{\,\times\,}}{ln}{\left({\mathtt{4}}\right)}\right)}} = {\mathtt{0.701\: \!838\: \!730\: \!514\: \!401}}$$