Hallo Anonymous,
ich sehe nur eine Möglichkeit: Faktorisieren !
0=2^x-3-4*2^-x $${\mathtt{0}} = {{\mathtt{2}}}^{{\mathtt{x}}}{\mathtt{\,-\,}}{\mathtt{3}}{\mathtt{\,-\,}}{\mathtt{4}}{\mathtt{\,\times\,}}{{\mathtt{2}}}^{{\mathtt{\,-\,}}{\mathtt{x}}}$$
0=2^-x*(2^x-4)*(2^x+1) $${\mathtt{0}} = \left({{\mathtt{2}}}^{{\mathtt{\,-\,}}{\mathtt{x}}}\right){\mathtt{\,\times\,}}\left({{\mathtt{2}}}^{{\mathtt{x}}}{\mathtt{\,-\,}}{\mathtt{4}}\right){\mathtt{\,\times\,}}\left({{\mathtt{2}}}^{{\mathtt{x}}}{\mathtt{\,\small\textbf+\,}}{\mathtt{1}}\right)$$
Die Gleichung wird =0 , wenn (2^x-4) = 0 ist => 2^x = 4 => x = 2
$${{\mathtt{2}}}^{{\mathtt{x}}}{\mathtt{\,-\,}}{\mathtt{4}} = {\mathtt{0}}$$ => $${{\mathtt{2}}}^{{\mathtt{x}}} = {\mathtt{4}}$$ => $${\mathtt{x}} = {\mathtt{2}}$$
Probe: $${{\mathtt{2}}}^{{\mathtt{2}}}{\mathtt{\,-\,}}{\mathtt{3}}{\mathtt{\,-\,}}{\mathtt{4}}{\mathtt{\,\times\,}}{{\mathtt{2}}}^{-{\mathtt{2}}} = {\mathtt{0}}$$
Gruß radix
!