\(\frac{15-\frac{15}{7}-\frac{15}{12}-\frac{15}{98}}{18-\frac{18}{7}-\frac{18}{12}-\frac{18}{98}}\)= \(\frac{15-15\left(\frac{1}{7}+\frac{1}{12}+\frac{1}{98}\right)}{18-18\left(\frac{1}{7}+\frac{1}{12}+\frac{1}{98}\right)}\)=\(\frac{15\left(1-\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}{18\left(1-\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}\)= \(\frac{15}{18}\)=\(\frac{5}{6}\)

cảm ơn nhìu

A=15x(1/7-1/12-1/98)/18(1/7-1/12-1/98)

A=15/18

A=5/6

h nhe!!!

\(A=\frac{15\left(1-\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}{18\left(1-\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}\)

\(A=\frac{15}{18}=\frac{5}{6}\)

\(A=\frac{15-\frac{15}{7}-\frac{15}{12}-\frac{15}{98}}{18-\frac{18}{7}-\frac{18}{12}-\frac{18}{98}}\)

\(\Rightarrow A=\frac{15\left(\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}{18\left(\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}\)

\(\Rightarrow A=\frac{15}{18}=\frac{5}{6}\)

mk làm chuẩn rồi nha

\(A=\frac{15\left(1-\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}{18\left(1-\frac{1}{7}-\frac{1}{12}-\frac{1}{18}\right)}=\frac{15}{18}\)

\(A=\frac{15\left(1-\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}{18\left(1-\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}=\frac{15}{18}=\frac{5}{6}\)

Ta có:

 A = [15 x (1-1/7-1/12-1/98)] / [ 18 x (1-1/7-1/12-1/98)]

  = 15/18 = 5/6

\(A=\frac{15\left(1-\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}{18\left(1-\frac{1}{7}-\frac{1}{12}-\frac{1}{98}\right)}=\frac{15}{18}=\frac{15:3}{18:3}=\frac{5}{6}\)

k cho mk nha

a = 2245/196

b =2211/161 dấu / có nghĩa là phân số bạn nhé 

Ta có \(\frac{-7}{6}=\frac{a-2}{18}\Rightarrow a-2=-21\Rightarrow a=-19\)

\(\frac{-7}{6}=\frac{-98}{3b+15}\Rightarrow3b+15=84\Rightarrow b=23\)

\(\frac{-7}{6}=\frac{14}{-5c+37}\Rightarrow-5c+37=-12\Rightarrow c=\frac{49}{5}\)

\(\frac{-7}{6}=\frac{d+1}{12}\Rightarrow d+1=-14\Rightarrow d=-15\)

\(\frac{7}{18}.\left(\frac{-12}{23}-\frac{4}{15}\right)+\frac{7}{18}.\left(\frac{8}{30}+\frac{35}{23}\right)\)

\(=\frac{7}{18}.\left(\frac{-12}{23}-\frac{4}{15}\right)+\frac{7}{18}.\left(\frac{4}{15}+\frac{35}{23}\right)\)

\(=\frac{7}{18}.\left(\frac{-12}{23}-\frac{4}{15}+\frac{4}{15}+\frac{35}{23}\right)\)

\(=\frac{7}{18}.[\left(\frac{-12}{23}+\frac{35}{23}\right)+\left(\frac{-4}{15}+\frac{4}{15}\right)]\)

\(=\frac{7}{18}.1+0\)

\(=\frac{7}{18}\)

_Chúc bạn học tốt_

a) $\frac{1}{6}:\frac{3}{7} = \frac{1}{6} \times \frac{7}{3} = \frac{7}{{18}}$  

b) $\frac{5}{{12}}:\frac{1}{4} = \frac{5}{{12}} \times \frac{4}{1} = \frac{{5 \times 4}}{{12 \times 1}} = \frac{{5 \times 4}}{{4 \times 3 \times 1}} = \frac{5}{3}$

c) $\frac{4}{{15}}:\frac{8}{3} = \frac{4}{{15}} \times \frac{3}{8} = \frac{{4 \times 3}}{{15 \times 8}} = \frac{{4 \times 3}}{{5 \times 3 \times 4 \times 2}} = \frac{1}{{10}}$          

d) $\frac{{18}}{5}:\frac{9}{{10}} = \frac{{18}}{5} \times \frac{{10}}{9} = \frac{{18 \times 10}}{{5 \times 9}} = \frac{{9 \times 2 \times 5 \times 2}}{{5 \times 9}} = 4$