Sao bạn đăng muộn vậy ??

Mik hay học khuya nha bạn!

65,42 x 3,5 : 3434,55

= 228,97 : 3434,55

= 1/15

1/15 nha ban

bn vào câu hỏi tương tự nha 

ket quả la 56m/giay

nho tk minh nha

\(\frac{2}{5}×\frac{3}{4}+\frac{6}{15}:\frac{4}{9}×5\)

\(=\frac{3}{10}+\frac{6}{15}×\frac{9}{4}×5\)

\(=\frac{3}{10}+\frac{9}{10}×5\)

\(=\frac{3}{10}+\frac{9}{2}\)

\(=\frac{3}{10}+\frac{45}{10}\)

\(=\frac{3+45}{10}\)

\(=\frac{48}{10}=\frac{24}{5}=4,8\)

\(\frac{3}{10}+\frac{9}{10}\cdot5=\frac{3}{10}+\frac{45}{10}=\frac{48}{10}=\frac{24}{5}\)

khong can ghi de bai nha

Đáp án là : \(\frac{7}{6}\)

Tk nha!!

\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}\)

\(=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}\)

\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}\)

\(=1-\frac{1}{8}=\frac{7}{8}\)

\(\frac{3}{10}+\frac{9}{2}\)

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

\(\frac{2}{5}\)x \(\frac{3}{4}\)+ \(\frac{6}{15}\): \(\frac{4}{9}\)x 5

= \(\frac{3}{10}\)+ \(\frac{6}{15}\)x \(\frac{9}{4}\)x 5

= \(\frac{18}{60}\)+ \(\frac{24}{60}\)x \(\frac{9}{4}\)x 5

= \(\frac{7}{10}\)x \(\frac{9}{4}\)x 5

= \(\frac{63}{40}\)x 5

= \(\frac{63}{8}\)

a) ta có: \(\frac{3}{4}< \frac{x}{8}< 1\)

\(\Rightarrow\frac{6}{8}< \frac{x}{8}< \frac{8}{8}\)

=> x = 7

b) ta có: \(\frac{5}{4}< x< \frac{27}{11}\)

\(\Rightarrow1,25< x< 2,45\)

=> x = 2

c)ta có:  \(1< \frac{4}{x}< 2\)

\(\frac{4}{4}< \frac{4}{x}< \frac{4}{2}\)

=> 4 > x > 2

=> x = 3

\(\frac{11}{9}+\frac{35}{18}\)

\(=\frac{19}{6}\)

\(\frac{22}{21}:\frac{1}{2}+\frac{25}{12}:\frac{1}{2}\)

\(\frac{44}{21}+\frac{25}{6}\)

\(\frac{263}{42}\)

57/18