Question

Упростите выражение (5/a-a/5) * (1/a-5+1/5+a)

Answer 1

$\displaystyle ( \frac{5}{a}- \frac{a}{5})( \frac{1}{a-5}+ \frac{1}{5+a})= \frac{25-a^{2}}{5a}* ( \frac{1}{5+a}-\frac{1}{5-a})= \\ \\ \\= \frac{25-a^{2}}{5a}* \frac{5-a-5-a}{25-a^{2}}= -\frac{2a}{5a}=-0,4$