13,
$\frac{9^10}{3^9.3^7}$
=$\frac{(3^2)^10}{3^16}$
=$\frac{3^20}{3^16}$
=3^4
14, $\frac{-2}{7}$ :$\frac{8}{11}$ +|-1,75|
=$\frac{-2}{7}$ .$\frac{11}{8}$ +1,75
=$\frac{-11}{28}$ +1,75
=$\frac{-11}{28}$ +$\frac{7}{4 }$
=$\frac{-11}{28}$ +$\frac{49}{28}$
=$\frac{38}{28}$
=$\frac{19}{14}$
5.|x+7/5|-1/5=0
=>|x+7/5|=1/5
=>x+7/5=±1/5
\(\left[ \begin{array}{l}x+7/5=1/5\\x+7/5=-1/5\end{array} \right.\) <=>\(\left[ \begin{array}{l}x=-6/5\\x=-8/5\end{array} \right.\)
