第9章 9.17

a3xa3xax+ax=(a3xa3x)(axax)(ax+ax)(axax)=a4xa2xa2x+a4xa2xa2x=32313+132313\frac{a^{3x} - a^{-3x}}{a^x + a^{-x}} = \frac{(a^{3x} - a^{-3x})(a^x - a^{-x})}{(a^x + a^{-x})(a^x - a^{-x})} = \frac{a^{4x} - a^{2x} - a^{-2x} + a^{-4x}}{a^{2x} - a^{-2x}} = \frac{3^2 - 3 - \frac{1}{3} + \frac{1}{3^2}}{3 - \frac{1}{3}}

=62983=52983=136= \frac{6 - \frac{2}{9}}{\frac{8}{3}} = \frac{\frac{52}{9}}{\frac{8}{3}} = \frac{13}{6}

解説: r31bn1z