Question

ПОМОГИТЕ ПРОШУ ВАС!!!!

Answer 1

$\displaystyle\bf \frac{z+11}{121-z^{2} } -\frac{11}{11z-z^{2} } =\frac{z+11}{(11-z)(11+z)}-\frac{11}{z(11-z)} =\\\\\\ =\frac{(z+11)\cdot z-11\cdot(11+z)}{z(11-z)(11+z)} =\frac{z^{2}+11z-121-11z }{z(121-z^{2} )} =\\\\\\ =\frac{z^{2}-121 }{z(121-z^{2}) } =-\frac{1}{z}$