Question

Даю 69 баллов за выполнение нескольких заданий.

Answer 1

Ответ:

3)а)$\frac{7}{12}*\frac{4}{21}+\frac{5}{12}*\frac{4}{21}=\frac{4}{21}*(\frac{7}{12}+\frac{5}{12})=\frac{4}{21} *\frac{12}{12}=\frac{4}{21}*1=\frac{4}{21}$

б)$2\frac{2}{17}*1\frac{5}{6}-1\frac{5}{6}*1\frac{2}{17}=1\frac{5}{6}*(2\frac{2}{17}-1\frac{2}{17})=1\frac{5}{6}*1=1\frac{5}{6}$

в)$(3\frac{4}{15}+4\frac{5}{6})(3\frac{17}{18}-2\frac{5}{9})=(\frac{49}{15}+\frac{29}{6})(3\frac{17}{18}-2\frac{10}{18})=\\=(\frac{49*2+29*5}{30})*1\frac{7}{18}=\frac{98+145}{30}*\frac{25}{18}=\frac{243}{30}*\frac{25}{18}=\frac{27}{6}*\frac{5}{2}=\frac{135}{12}=\\=11\frac{3}{12}=11,25$

4)0,8(х-2)=0

0,8 = 0   или   х-2 = 0

Ложь               х = 2

Ответ: х = 2.

5)а)$\frac{3a}{4y}$

б)$\frac{2}{7}x*1.4*\frac{1}{5}=\frac{2}{7}*\frac{14}{10}*\frac{1}{5}*x=\frac{2}{1}*\frac{2}{10}*\frac{1}{5}*x=\frac{4x}{50}=\frac{2x}{25}$