Question

Решите 2. Дам 35 баллов

Answer 1

$\displaystyle 1).\ \ \frac{1}{5}+\frac{1}{3}= \frac{3}{15}+\frac{5}{15}= \frac{8}{15}; \\ \\2).\ \ \frac{1}{2}+\frac{3}{8}= \frac{4}{8}+\frac{3}{8}= \frac{7}{8}=0,875; \\ \\ 3).\ \ \frac{3}{4}+2=2\frac{3}{4}=2,75 \\ \\ 4).\ \ \frac{7}{12}-1=\frac{7}{12}-\frac{12}{12}= -\frac{5}{12}; \\ \\ 5).\ \ \frac{4}{5}-\frac{9}{10}=\frac{8}{10}-\frac{9}{10}=- \frac{1}{10}=-0,1 \\ \\ 6).\ \ \frac{1}{3}-\frac{1}{2}=\frac{2}{6}-\frac{3}{6}=- \frac{1}{6}; \\\\ 7).\ \ 1+ \frac{7}{3}=1+2\frac{1}{3}=3\frac{1}{3};$

$\displaystyle 8).\ \ \frac{8}{15}:4=\frac{8}{15}*\frac{1}{4}=\frac{8}{60}=\frac{2}{15};\\\\9).\ \ 3:\frac{3}{2}=3*\frac{2}{3}=2;\\\\10).\ \ -1:\frac{3}{4}=-1*\frac{4}{3}=-1 \frac{1}{3};\\\\11).\ \ -\frac{7}{12}:(-\frac{1}{4})=\frac{7}{12}*4=\frac{7}{3}=2\frac{1}{3};\\\\12).\ \ -\frac{3}{4}:\frac{4}{9}=-\frac{3}{4}*\frac{9}{4}=-\frac{27}{16}=-1\frac{11}{16};\\\\13).\ \ \frac{7}{9}*\frac{18}{35}=\frac{7}{9}*\frac{2*9}{5*7}= \frac{2}{5}=0,4$

$\displaystyle 14).\ \ -\frac{4}{19}*(-\frac{57}{64})= \frac{4}{19}*\frac{3*19}{4*16}= \frac{3}{16}; \\ \\ 15).\ \ 2\frac{3}{4}+3\frac{5}{7}=5+(\frac{21}{28}+\frac{20}{28})=5\frac{41}{28}=6\frac{13}{28}; \\ \\ 16).\ \ -4\frac{2}{3}+7\frac{1}{2}= \frac{15}{2}-\frac{14}{3}= \frac{45}{6}-\frac{28}{6}= \frac{17}{6}=2\frac{5}{6}; \\ \\ 17).\ \ 4\frac{1}{3}+\frac{3}{17}=4+( \frac{17}{51}+\frac{9}{51})=4 \frac{26}{51}; \\ \\ 18).\ \ - 5\frac{2}{5}+4\frac{1}{3}=4 \frac{5}{15}-5\frac{6}{15}=-1 \frac{1}{15};$

$\displaystyle 19).\ \ 6\frac{1}{2}-3\frac{3}{4}= 5\frac{6}{4}-3\frac{3}{4}=2\frac{3}{4}=2,75; \\ \\ 20).\ \ 2\frac{1}{2}-7\frac{5}{6}= \frac{15}{6}-\frac{47}{6}=- \frac{32}{6}=-5\frac{1}{3}; \\ \\ 21).\ \ -4\frac{2}{3}-7\frac{7}{9}=-(4\frac{6}{9}+7\frac{7}{9})=-11 \frac{13}{9}=-12\frac{4}{9}; \\ \\ 22).\ \ -2\frac{2}{3}-3\frac{5}{9}=-(2\frac{6}{9}+3\frac{5}{9})=-5\frac{11}{9}=-6\frac{2}{9};$

$\displaystyle 23).\ \ 2\frac{3}{4}*5\frac{7}{33}=\frac{11}{4}*\frac{172}{33}=\frac{43}{3}=14\frac{1}{3}; \\ \\ 24).\ \ -3\frac{1}{2}*2\frac{2}{5}=-\frac{7}{2}*\frac{12}{5}=-\frac{42}{5}=-8 \frac{2}{5}=-8,4; \\ \\ 25).\ \ -4\frac{5}{7}*(-2\frac{6}{11})=\frac{33}{7}*\frac{28}{11}=12; \\ \\ 26).\ \ -3\frac{1}{2}*2\frac{2}{7}=-\frac{7}{2}*\frac{16}{7}=-8; \\ \\ 27).\ \ 4\frac{1}{3}:2\frac{5}{6}=\frac{13}{3}*\frac{6}{17}=\frac{26}{17}=1\frac{9}{17};$

$\displaystyle 28).\ \ -7\frac{3}{8}:(-2\frac{1}{16})= \frac{59}{8}* \frac{16}{33}= \frac{118}{33}=3 \frac{19}{33}; \\ \\ 29).\ \ -1 \frac{1}{3}:3 \frac{1}{6}=- \frac{4}{3}* \frac{6}{19}=- \frac{8}{19}; \\ \\ 30).\ \ 4 \frac{1}{5}:7 \frac{1}{25}= \frac{21}{5}* \frac{25}{176}= \frac{105}{176};$