a: \(=\left(\dfrac{2}{18}-\dfrac{15}{18}-\dfrac{72}{18}\right):\left(\dfrac{21}{36}-\dfrac{1}{36}-\dfrac{360}{36}\right)\)

\(=\dfrac{-85}{18}:\dfrac{-170}{18}\)

\(=\dfrac{85}{170}=\dfrac{1}{2}\)

b: \(=\left(\dfrac{5}{8}-\dfrac{5}{6}-\dfrac{5}{32}+\dfrac{5}{64}\right):\left(1-\dfrac{1}{2}-\dfrac{1}{4}+\dfrac{1}{8}\right)\)

\(=\dfrac{-55}{192}:\dfrac{3}{8}=\dfrac{-55}{192}\cdot\dfrac{8}{3}=-\dfrac{55}{72}\)

-575/756                    

Bạn nhóm ra tương tự như 2 bài trước thôi

\(H=\frac{\frac{15}{8}-\frac{15}{6}-\frac{15}{32}+\frac{15}{63}}{3-\frac{3}{2}-\frac{3}{4}+\frac{3}{8}}\)

\(H=\frac{15\left(\frac{1}{8}-\frac{1}{6}-\frac{1}{32}+\frac{1}{63}\right)}{3\left(1-\frac{1}{2}-\frac{1}{4}+\frac{1}{8}\right)}\)

\(H=\frac{15\left[\left(\frac{1}{8}-\frac{1}{32}\right)-\frac{1}{6}+\frac{1}{63}\right]}{3\left[\left(1+\frac{1}{8}\right)-\frac{1}{2}-\frac{1}{4}\right]}\)

\(H=\frac{15\left[\frac{3}{32}-\frac{1}{6}+\frac{1}{63}\right]}{3\left[\frac{9}{8}-\frac{4}{8}-\frac{2}{8}\right]}\)

\(H=\frac{15\left[\frac{-7}{96}+\frac{1}{63}\right]}{3\cdot\frac{3}{8}}\)

\(H=\frac{15\left[\frac{-147}{2016}+\frac{32}{2016}\right]}{\frac{9}{8}}\)

\(H=\frac{15\cdot\frac{-115}{2016}}{\frac{9}{8}}\)

\(H=\frac{15\cdot\frac{-115}{2016}-\frac{2153}{2016}+\frac{2153}{2016}}{\frac{9}{8}}\)

\(H=\frac{15\cdot\frac{-2268}{2016}+\frac{2153}{2016}}{\frac{9}{8}}\)

\(H=\frac{15\cdot\frac{-9}{8}}{\frac{9}{8}}+\frac{\frac{2153}{2016}}{\frac{9}{8}}\)

\(H=\frac{-15\cdot\frac{9}{8}}{\frac{9}{8}}+\frac{\frac{2268}{2016}}{\frac{9}{8}}-\frac{\frac{115}{2016}}{\frac{9}{8}}\)

\(H=-15+1-0,0507054674 \)

\(H=-14-0,0507054674 \)

\(H=-14,0507055\)

\(=\left(\frac{15}{8}-\frac{15}{6}-\frac{15}{32}+\frac{15}{63}\right):\left(3-\frac{3}{2}-\frac{3}{4}+\frac{3}{8}\right)\)

\(=\left(\frac{3780}{2016}-\frac{5040}{2016}-\frac{945}{2016}+\frac{480}{2016}\right):\left(\frac{24}{8}-\frac{12}{8}-\frac{6}{8}+\frac{3}{8}\right)\)

\(=\frac{-575}{672}:\frac{9}{8}=\frac{-575}{672}.\frac{8}{9}=\frac{-575}{756}\)

giúp với ạ

giải dc nhưng mà hoi lâu

a)\(\dfrac{5}{7}+\dfrac{4}{9}=\dfrac{45}{63}+\dfrac{28}{63}=\dfrac{73}{63}\) ; \(\dfrac{9}{11}+\dfrac{3}{8}=\dfrac{72}{88}+\dfrac{33}{88}=\dfrac{105}{88}\)

\(\dfrac{4}{5}-\dfrac{2}{3}=\dfrac{12}{15}-\dfrac{10}{15}=\dfrac{2}{15}\); \(\dfrac{16}{25}-\dfrac{2}{5}=\dfrac{16}{25}-\dfrac{10}{25}=\dfrac{6}{25}\)

a: \(=\left(-\dfrac{25}{140}+\dfrac{245}{140}+\dfrac{32}{140}\right)\cdot\dfrac{-69}{20}\)

\(=\dfrac{252}{140}\cdot\dfrac{-69}{20}\)

\(=\dfrac{9}{5}\cdot\dfrac{-69}{20}=\dfrac{-621}{100}\)

b: \(=\left(6-2-\dfrac{4}{5}\right)\cdot\dfrac{25}{8}-\dfrac{8}{5}\cdot4\)

\(=\dfrac{16}{5}\cdot\dfrac{25}{8}-\dfrac{32}{5}=\dfrac{18}{5}\)

c: \(=\left(\dfrac{2}{24}+\dfrac{18}{24}+\dfrac{14}{24}\right):\dfrac{-17}{8}\)

\(=\dfrac{34}{24}\cdot\dfrac{-8}{17}=\dfrac{-1}{3}\cdot2=-\dfrac{2}{3}\)

Để nhân các phân số này, ta chỉ cần nhân tử số với nhau và mẫu số với nhau:

\[
\frac{1}{3} \times \frac{2}{5} \times \frac{3}{7} \times \frac{4}{9} \times \frac{5}{11} \times \frac{6}{15} \times \frac{7}{15} \times \frac{8}{15} \times \frac{9}{19} \times \frac{10}{21} \times \frac{11}{32} \times \frac{12}{25} \times \left( \frac{126}{252} - 4 \right)
\]

Sau đó, ta thực hiện các phép tính:

1. Nhân tử số:
\[1 \times 2 \times 3 \times 4 \times 5 \times 6 \times 7 \times 8 \times 9 \times 10 \times 11 \times 12 \times 126 = 997920\]

2. Nhân mẫu số:
\[3 \times 5 \times 7 \times 9 \times 11 \times 15 \times 15 \times 15 \times 19 \times 21 \times 32 \times 25 \times 252 = 7621237680\]

Kết quả là:
\[\frac{997920}{7621237680}\]

Bây giờ, ta có thể rút gọn phân số này bằng cách chia tử số và mẫu số cho 160:

\[ \frac{997920}{7621237680} = \frac{997920 ÷ 160}{7621237680 ÷ 160} = \frac{6237}{47695230} \]

A/   \(\left(15-6\frac{13}{18}\right):11\frac{1}{27}-2\frac{1}{8}:1\frac{11}{40}\)

\(=\left(15-\frac{121}{18}\right):\frac{298}{27}-\frac{17}{8}:\frac{51}{40}\)

\(=\left(\frac{270}{18}-\frac{121}{18}\right):\frac{298}{27}-\frac{17}{8}:\frac{51}{40}\)

\(=\frac{149}{18}:\frac{298}{27}-\frac{17}{8}:\frac{51}{40}\)

\(=\frac{3}{4}-\frac{5}{3}\)

\(=\frac{9}{12}-\frac{20}{12}\)\(=-\frac{11}{12}\)

B/  \(\left(-3,2\right)\cdot-\frac{15}{64}+\left(0,8-2\frac{4}{15}\right):3\frac{2}{3}\)

\(=\left(-3,2\right)\cdot-\frac{15}{64}+\left(0,8-\frac{34}{15}\right):\frac{11}{3}\)

\(=-\frac{3,2}{1}\cdot-\frac{15}{64}+\left(0,8-\frac{34}{15}\right):\frac{11}{3}\)

\(=\frac{48}{64}+\left(0,8-\frac{34}{15}\right):\frac{11}{3}\)

\(=\frac{3}{4}+\left(\frac{12}{15}-\frac{34}{15}\right):\frac{11}{3}\)

\(=\frac{3}{4}+\left(-\frac{22}{15}\right):\frac{11}{3}\)

\(=\frac{3}{4}+\left(-\frac{2}{5}\right)\)

\(=\frac{15}{20}+\left(-\frac{8}{20}\right)\)

\(=\frac{7}{20}\)