Question

УПРОСТИТЕ ВЫРАЖЕНИЕ1!!!!!!!!!!!!!!!!!!!

Answer 1

$1)\frac{a-3b}{a^{2}+3ab }-\frac{a+3b}{a^{2} -3ab}=\frac{a-3b}{a(a+3b)}-\frac{a+3b}{a(a-3b)}=\frac{a^{2} -6ab+b^{2}-a^{2}-6ab-b^{2}}{a(a+3b)(a-3b)}=\frac{-12ab}{a(a^{2}-9b^{2})} \\\\2)-\frac{12ab}{a(a^{2}-9b^{2})}:\frac{4b^{2}}{9b^{2}-a^{2}}=\frac{12ab}{a(9b^{2}-a^{2})}*\frac{9b^{2}-a^{2}}{4b^{2}}=\frac{3}{b}$