Question

помогите пожалуйста. ​

Answer 1

$\displaystyle \frac{9x^{-2}}{8-x^{-2}} -\frac{9x^{-2}}{8+x^{-2}}=\frac{9}{x^2(8-x^{-2})}-\frac{9}{x^2(8+x^{-2})}=\frac{9(8+x^{-2})-9(8-x^{-2})}{x^2(8-x^{-2})(8+x^{-2})} =\\\\=\frac{9(8+x^{-2}-8+x^{-2})}{x^2(8-x^{-2})(8+x^{-2})} =\frac{18x^{-2}}{x^2(8-x^{-2})(8+x^{-2})}=\frac{18}{x^4(8-x^{-2})(8+x^{-2})} =\\=\frac{18}{x^4(64-x^{-4})} =\frac{18}{64x^4-1}$

При х=0,2⁻¹

$\displaystyle \frac{18}{64\times (0,2^{-1})^4-1} =\frac{18}{64\times5^4-1} =\frac{18}{39999} =\frac{6}{13333}$

$x=0,2^{-1}=5$