Упростите и найдите значение выражения:
а) $\frac{5}{7}а + \frac{3}{14}а$ при $а = 4\frac{2}{3}; \frac{7}{13}$;
б) $\frac{3}{8}y + y - \frac{1}{4}y$ при $y = 2\frac{2}{3}; \frac{4}{9}$;
в) $\frac{13}{15}m - \frac{3}{4}m + \frac{1}{12}m$ при $m = 2\frac{1}{2}; 6\frac{1}{4}$;
г) $\frac{1}{3}х + \frac{3}{4}х - \frac{4}{9}х$ при $х = 1\frac{13}{23}; \frac{9}{46}$.
$\frac{5}{7}а + \frac{3}{14}а = \frac{10}{14}а + \frac{3}{14}а = \frac{13}{14}а$
при $а = 4\frac{2}{3}, \frac{13}{14}а = \frac{13}{14} * 4\frac{2}{3} = \frac{13}{14} * \frac{14}{3} = \frac{13}{1} * \frac{1}{3} = \frac{13}{3} = 4\frac{1}{3}$;
при $а = \frac{7}{13}, \frac{13}{14}а = \frac{13}{14} * \frac{7}{13} = \frac{1}{2} * \frac{1}{1} = \frac{1}{2}$.
$\frac{3}{8}y + y - \frac{1}{4}y = \frac{3}{8}y + \frac{8}{8}y - \frac{2}{8}y = \frac{9}{8}y$
при $y = 2\frac{2}{3}, \frac{9}{8}y = \frac{9}{8} * 2\frac{2}{3} = \frac{9}{8} * \frac{8}{3} = \frac{3}{1} * \frac{1}{1} = 3$;
при $y = \frac{4}{9}, \frac{9}{8}y = \frac{9}{8} * \frac{4}{9} = \frac{1}{2} * \frac{1}{1} = \frac{1}{2}$.
$\frac{13}{15}m - \frac{3}{4}m + \frac{1}{12}m = \frac{52}{60}m - \frac{45}{60}m + \frac{5}{60}m = \frac{12}{60}m = \frac{1}{5}m$
при $m = 2\frac{1}{2}, \frac{1}{5}m = \frac{1}{5} * 2\frac{1}{2} = \frac{1}{5} * \frac{5}{2} = \frac{1}{1} * \frac{1}{2} = \frac{1}{2}$;
при $m = 6\frac{1}{4}, \frac{1}{5}m = \frac{1}{5} * 6\frac{1}{4} = \frac{1}{5} * \frac{25}{4} = \frac{1}{1} * \frac{5}{4} = 1\frac{1}{4}$.
$\frac{1}{3}х + \frac{3}{4}х - \frac{4}{9}х = \frac{12}{36}х + \frac{27}{36}х - \frac{16}{36}х = \frac{23}{36}х$
при $х = 1\frac{13}{23}, \frac{23}{36}х = \frac{23}{36} * 1\frac{13}{23} = \frac{23}{36} * \frac{36}{23} = 1$;
при $х = \frac{9}{46}, \frac{23}{36}х = \frac{23}{36} * \frac{9}{46} = \frac{1}{4} * \frac{1}{2} = \frac{1}{8}$.
Пожауйста, оцените решение
