0\\\frac{2}{t}-8t-15=0\ \ \ \ \ \ \ \ |*t\\2-8t^2-15t=0\\8t^2+15t-2=0\\D=225+64=289=17^2\\t_1=\frac{-15+17}{16}=\frac{2}{16}=\frac{1}{8}\\t_2=\frac{-15-17}{16}=-\frac{32}{16}=-2" alt="2^{1-x}-2^{3+x}-15=0\\2^1*2^{-x}-2^3*2^x-15=0\\\frac{2}{2^x}-8*2^x-15=0\\\\2^x=t,\ t>0\\\frac{2}{t}-8t-15=0\ \ \ \ \ \ \ \ |*t\\2-8t^2-15t=0\\8t^2+15t-2=0\\D=225+64=289=17^2\\t_1=\frac{-15+17}{16}=\frac{2}{16}=\frac{1}{8}\\t_2=\frac{-15-17}{16}=-\frac{32}{16}=-2" align="absmiddle" class="latex-formula">
t₂∉t>0