\[\mathbf{Страница\ 89.}\]
\[\boxed{\mathbf{1.}}\]
\[\textbf{а)}\ положительные.\]
\[\textbf{б)}\ умножить.\]
\[\textbf{в)}\ умножить.\]
\[\textbf{г)}\ единице.\]
\[\textbf{д)}\ числителя\text{\ p\ }на\ \]
\[знаменатель\ \text{q.}\ \]
\[\boxed{\mathbf{2.}}\]
\[\textbf{а)} - 2607 \cdot 305 = - 795\ 135\]
\[\textbf{б)}\ 229\ 616\ :( - 452) = - 508\]
\[\textbf{в)} - 134\ 318\ :( - 562) = 239\]
\[\boxed{\mathbf{3.}}\]
\[\textbf{а)}\ \frac{72}{128}\ :\frac{102}{110} = \frac{72}{128} \cdot \frac{110}{102} =\]
\[= \frac{9 \cdot 55}{16 \cdot 51} = \frac{3 \cdot 55}{16 \cdot 17} = \frac{165}{272}\]
\[\textbf{б)}\ \frac{43}{44} \cdot \frac{55}{172} = \frac{5}{4 \cdot 4} = \frac{5}{16}\]
\[\textbf{в)}\ \frac{17}{18} \cdot 36 = 17 \cdot 2 = 34\]
\[\textbf{г)}\ \frac{26}{27} \cdot 81 = 26 \cdot 3 = 78\]
\[\textbf{д)}\ \frac{216}{405} \cdot \frac{81}{252} = \frac{6}{5 \cdot 7} = \frac{6}{35}\]
\[\textbf{е)}\ 64\ :\frac{8}{9} = 64 \cdot \frac{9}{8} = 8 \cdot 9 = 72\]
\[\textbf{ж)}\ 72\ :\frac{12}{13} = 72 \cdot \frac{13}{12} = 6 \cdot 13 =\]
\[= 78\]
\[\textbf{з)}\ \frac{108}{48}\ :6 = \frac{108}{48} \cdot \frac{1}{6} = \frac{18}{48} = \frac{3}{8}\]