Question

с дробямм... сегодня надо сдать(

Answer 1

Объяснение:

а)

$\frac{4}{7}*\frac{14}{5}:\frac{2}{5} = \frac{4}{7}*\frac{14}{5}*\frac{5}{2} =\frac{4*14*5}{7*5*2} =\frac{4*14*5}{14*5}=4 \ \in \mathbb N; \\$

б)

$(\frac{1}{2} -\frac{5}{8}):\frac{1}{8}= \frac{1*4-5*1}{8}*\frac{8}{1}=\frac{(4-5)*8}{8}=-1\ \in \mathbb Z;$

в)

$(\frac{3}{4}-\frac{2}{3})*\frac{6}{5}=\frac{3*3-2*4}{3*4} *\frac{6}{5}=\frac{(9-8)*6}{12*5}=\frac{1}{10}\ \in\mathbb Q;\\$

г)

$\frac{7}{15}*\frac{5}{7}-3:9=\frac{1}{3} -\frac{1}{3}=0\ \notin \mathbb N;$

д)

$\frac{2}{3}*(1-\frac{5}{6}):\frac{1}{3} =\frac{2}{3}*\frac{1}{6} *\frac{3}{1}=\frac{2*1*3}{3*6*1} =\frac{1}{3}\ \in \mathbb Q;$

e)

$\frac{6}{7} :(2-\frac{5}{7})*\frac{1}{2} =\frac{6}{7}:1\frac{2}{7} *\frac{1}{2} = \frac{6}{7}:\frac{9}{7} *\frac{1}{2} =\frac{6}{7}*\frac{7}{9} *\frac{1}{2} = \frac{6*7*1}{7*9*2}=\frac{1}{3} \ \notin \mathbb Z.$