a/ 56

b/ 15

c/ 27

d/275

e/ 738

f/  90

g/ 3300

\(\frac{2}{7}:y=\frac{10}{21}.\frac{9}{14}\)

\(\frac{2}{7}:y=\frac{15}{49}\)

\(y=\frac{2}{7}:\frac{15}{49}\)

\(y=\frac{2}{7}.\frac{49}{15}\)

\(y=\frac{14}{15}\)

\(y-\frac{1}{3}=\frac{10}{21}:\frac{15}{28}\)

\(y-\frac{1}{3}=\frac{10}{21}.\frac{28}{15}\)

\(y-\frac{1}{3}=\frac{8}{9}\)

\(y=\frac{8}{9}+\frac{1}{3}\)

\(y=\frac{8}{9}+\frac{3}{9}\)

\(y=\frac{11}{9}\)

a) Ta có :  \(y-\frac{1}{3}=\frac{10}{21}\div\frac{15}{28}\)

\(\Rightarrow\)       \(y-\frac{1}{3}=\frac{8}{9}\)

\(\Rightarrow\)       \(y\)        \(=\frac{8}{9}+\frac{1}{3}\)

\(\Rightarrow\)      \(y\)         \(=\frac{11}{9}\)

Vậy \(y=\frac{11}{9}\)

b) Ta có : \(\frac{2}{7}\div y=\frac{10}{21}\times\frac{9}{14}\) 

\(\Rightarrow\)      \(\frac{2}{7}\div y=\frac{15}{49}\)

\(\Rightarrow\)                  \(y=\frac{2}{7}\div\frac{15}{49}\)      

\(\Rightarrow\)                  \(y=\frac{14}{15}\)

Vậy \(y=\frac{14}{15}\)

                     Cbht !!!

10/23 nha bạn

A \(\frac{10}{23}\)

a) \(\frac{2}{5}+\frac{9}{15}=\frac{2}{5}+\frac{3}{5}=\frac{5}{5}=1\)

b) \(\frac{15}{45}+\frac{25}{30}=\frac{1}{3}+\frac{5}{6}=\frac{2}{6}+\frac{5}{6}=\frac{7}{6}\)

c) \(\frac{28}{32}+\frac{45}{72}=\frac{7}{8}+\frac{5}{8}=\frac{12}{8}=\frac{3}{2}\)

d) \(\frac{8}{28}+\frac{5}{30}=\frac{2}{7}+\frac{1}{6}=\frac{12}{42}+\frac{7}{42}=\frac{19}{42}\)

a) \(\frac{2}{5}+\frac{9}{15}\)=\(\frac{2}{5}+\frac{3}{5}=\frac{2+3}{5}=1\)

b)\(\frac{15}{45}+\frac{25}{30}=\frac{1}{3}+\frac{5}{6}=\frac{2}{6}+\frac{5}{6}=\frac{2+5}{6}=\frac{7}{6}\)

c)\(\frac{28}{32}+\frac{45}{72}=\frac{7}{8}+\frac{5}{8}=\frac{7+5}{8}=\frac{12}{8}=\frac{3}{2}\)

d)\(\frac{8}{28}+\frac{5}{30}=\frac{2}{7}+\frac{1}{6}=\frac{12}{42}+\frac{7}{42}=\frac{12+7}{42}=\frac{19}{42}\)

Bạn tự làm bài nếu bạn không tính được thì bạn hỏi cô hay thầy đấy nha bạn,chúc bạn học giỏi nha:

a, \(\frac{39}{19}\)

b, \(8.5\)hay \(\frac{17}{2}\)

c, \(\frac{1277}{4186}\)

Bấm máy tính là được ^_^

\(.\)

Câu 1:\(\frac{12}{23}\times\frac{9}{28}+\frac{11}{23}\times\frac{9}{28}\)

\(=\frac{9}{28}\times\left(\frac{12}{23}+\frac{11}{23}\right)\)

\(=\frac{9}{28}\times\frac{23}{23}\)

\(=\frac{9}{28}\times1\)

\(=\frac{9}{28}\)

Câu 2:

\(3+\frac{1}{9}+\frac{3}{9}+2+\frac{5}{9}+3+2\)

\(=\left(3+2+2+3\right)+\left(\frac{1}{9}+\frac{3}{9}+\frac{5}{9}\right)\)

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

\(=10+1\)

\(=11\)

\(\frac{12}{23}x\frac{9}{28}+\frac{11}{23}x\frac{9}{28}=\)\(\left(\frac{12}{23}+\frac{11}{23}\right)x\frac{9}{28}\)\(=\) \(1x\frac{9}{28}=\frac{9}{28}\)

\(3+\frac{1}{9}+\frac{3}{9}+2+\frac{5}{9}+3+2\)\(=\) \(\left(\frac{1}{9}+\frac{3}{9}+\frac{5}{9}\right)+\left(3+2+3+2\right)\)\(=\) \(1+3+2+3+2=\)\(11\) 

\(a.\) \(\frac{4}{15}.\frac{7}{9}+\frac{4}{15}.\frac{2}{9}\)

\(=\frac{4}{15}\left(\frac{7}{9}+\frac{2}{9}\right)\)

\(=\frac{4}{15}.\frac{9}{9}\)

\(=\frac{4}{15}.1\)

\(=\frac{4}{15}\)

\(b.\) \(\frac{13}{19}.\frac{23}{11}-\frac{13}{19}.\frac{8}{11}-\frac{13}{19}.\frac{4}{11}\)

\(=\frac{13}{19}\left(\frac{23}{11}-\frac{8}{11}-\frac{4}{11}\right)\)

\(=\frac{13}{19}.\frac{11}{11}\)

\(=\frac{13}{19}.1\)

\(=\frac{13}{19}\)

a)4/15 x(7/9+2/9)=4/15x1=4/15

b)13/19x(23/11-8/11-4/11)13/19x1=13/19

Haha

cuoi lol

a, 10000

b, 10100

k mk nha

bạn ơi cách làm như thế nào?