Question

Найдите значение выражения: 5/12а+7при а=4; 4/9b+2/3приb=6; 2/5+1 1/4a при а=2; 2 3/10b+1/2 при b= 5 поогите правильно все напишите

Answer 1

 $\displaystyle \frac{5}{12}a+7; a=4\\\\ \frac{5}{12}*4+7= \frac{5*4}{12}+7= \frac{5}{3}+7=8 \frac{2}{3}$

$\displaystyle \frac{4}{9}b+ \frac{2}{3}; b=6\\\\ \frac{4}{9}*6+ \frac{2}{3}= \frac{4*2}{3}+ \frac{2}{3}= \frac{10}{3}=3 \frac{1}{3}$

$\displaystyle \frac{2}{5}+1 \frac{1}{4}a; a=2\\\\ \frac{2}{5}+ \frac{5}{4}*2= \frac{2}{5}+ \frac{5}{2}= \frac{29}{10}=2.9$

$\displaystyle 2 \frac{3}{10}b+ \frac{1}{2}; b=5\\\\ \frac{23}{10}*5+ \frac{1}{2}= \frac{23}{2}+ \frac{1}{2}= \frac{24}{2}=12$

Answer 2

А) $\frac{5}{12a+7}$ при a = 4
 $\frac{5}{12*4+7}= \frac{5}{55} = \frac{1}{11}$
б) $\frac{4}{9b} + \frac{2}{3}$ при b = 6
$\frac{4}{9*6} + \frac{2}{3} = \frac{4}{54} + \frac{2}{3} = \frac{4}{54} + \frac{36}{54}= \frac{40}{54} = \frac{20}{27}$
в) $\frac{2}{5} + 1 \frac{1}{4a}$ при a = 2
$\frac{2}{5} + 1 \frac{1}{4*2} = \frac{2}{5} + \frac{9}{8} = \frac{16}{40} + \frac{45}{40} = \frac{61}{40} = 1 \frac{21}{40}$
г) $2 \frac{3}{10b} + \frac{1}{2}$ при b = 5
 $2 \frac{3}{10*5} + \frac{1}{2} = \frac{103}{50} + \frac{25}{50} = \frac{128}{50} = 2\frac{14}{25}$