-575/756                    

Bạn nhóm ra tương tự như 2 bài trước thôi

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

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

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

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

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

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

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

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

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

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

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

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

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

\(H=-14,0507055\)

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

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

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

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:

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

\(\frac{1}{2}+\frac{5}{6}-\frac{3}{8}\)

\(=\frac{12}{24}+\frac{20}{24}-\frac{9}{24}\)

\(=\frac{23}{24}\)

\(\frac{10}{15}\cdot\frac{7}{4}+\frac{7}{4}\cdot\frac{9}{15}-\frac{4}{15}\cdot\frac{7}{4}\)

\(=\frac{7}{4}\cdot\left(\frac{10}{15}+\frac{9}{15}-\frac{4}{15}\right)\)

\(=\frac{7}{4}\cdot1=\frac{7}{4}\)

\(\left(\frac{4}{5}+\frac{1}{2}\right)\left(\frac{3}{13}-\frac{8}{13}\right)\)

\(=\left(\frac{8}{10}+\frac{5}{10}\right)\cdot\left(-\frac{5}{13}\right)\)

\(=\frac{13}{10}\cdot\left(-\frac{5}{13}\right)=-\frac{1}{2}\)

a,  3x-12 = 30 

=> 3x = 30 + 12

=> 3x = 42 

=> x = 42 : 3  = 14 

Vậy x = 14 

b, \(\frac{2}{3}x+\frac{1}{4}=\frac{7}{12}\)

\(\Rightarrow\frac{2}{3}x=\frac{7}{12}-\frac{1}{4}\)

\(\Rightarrow\frac{2}{3}x=\frac{7}{12}-\frac{3}{12}\)

\(\Rightarrow\frac{2}{3}x=\frac{1}{3}\)

\(\Rightarrow x=\frac{1}{3}\div\frac{2}{3}\Rightarrow\frac{1}{3}\cdot\frac{3}{2}=\frac{1}{2}\)

Vậy x = \(\frac{1}{2}\)

c, 2x² = 32 

=> x² = 32 : 2 

=> x² = 16

=> x² = 4² 

=> x = 4 

Vậy x = 4 

thanhks anh nhé!

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

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

\(\frac{15}{41}+\frac{-138}{41}< x< \frac{1}{2}+\frac{1}{3}+\frac{1}{6}\)

\(\Leftrightarrow\frac{-123}{41}< x< \frac{1.3+1.2+1}{6}\)

\(\Leftrightarrow-3< x< 1\)

\(\Rightarrow x\in\left\{-2;-1;0\right\}\)

\(\frac{x}{5}=\frac{15}{2}-\frac{51}{10}\)

\(\frac{x}{5}=\frac{15.5-51}{10}\)

\(\frac{x}{5}=\frac{24}{10}\)

\(\frac{x}{5}=\frac{12}{5}\)

\(x=12\)

\(\frac{2x}{3}-\frac{1}{9}=\frac{59}{36}+\frac{1}{4}\)

\(\frac{2x}{3}-\frac{1}{9}=\frac{59+9}{36}\)

\(\frac{2x}{3}-\frac{1}{9}=\frac{68}{36}\)

\(\frac{2x}{3}=\frac{68}{36}+\frac{1}{9}\)

\(\frac{2x}{3}=\frac{68}{36}+\frac{4}{36}\)

\(\frac{2x}{3}=2\)

\(\Rightarrow2x=6\)

\(\Rightarrow x=3\)