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

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

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

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

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

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

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

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

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

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

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

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 !!!

Đề bài là gì bạn ơi có chỗ ...

chưa có đề bạn ơi! Y_Y

Hok tốt ^_^

a)\(\frac{2}{3}\)

b)\(\frac{3}{4}\)

\(a,\frac{1}{2}\times\frac{4}{5}\div\frac{6}{10}\)

\(=\frac{2}{5}\div\frac{6}{10}\)

\(=\frac{2}{5}\times\frac{10}{6}\)

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

\(b,\frac{24}{35}\div\left(\frac{4}{5}\times\frac{8}{7}\right)\)

\(=\frac{24}{35}\div\frac{32}{35}\)

\(=\frac{24}{35}\times\frac{35}{32}\)

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

a,

\(=\frac{1+2+3+4+5+6+7+8+9}{10}=\frac{45}{10}=\frac{9}{2}\)

b,\(=9\times\left(\frac{26\times10101}{27\times10101}+\frac{8\times11111}{9\times11111}\right)=9\times\left(\frac{26}{27}+\frac{8}{9}\right)=9\times\frac{50}{27}=\frac{50}{3}\)

k cho mk nha!!!!!!!!!!!!!

Mk cần gấp các bạn ơi !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!?

GIẢI

Tính : 

8/2 + 5/2 = 13/2   

5/10 + 5/10 = 10/10 = 1

4/10 + 5/10 = 9/10

6/7 + 1/7 = 7/7 = 1

HỌC TỐT

            Giải

8/2 + 5/2 = 13/2                                               5/10 + 5/10 = 10/10 = 1 

4/10 + 5/10 = 9/10                                           6/7 + 1/7 = 7/7 = 1

\(\frac{2}{5}=\frac{4}{10}\)

\(\frac{12}{30}=\frac{4}{10}\)

\(\frac{72}{45}=\frac{8}{5}\)

\(\frac{1}{4}=\frac{7}{28}\)

2/5=4/10

12/30=4/10

72/45=8/5

1/4=7/28

ps <\(\frac{1}{2}\) là:

\(\frac{1}{10}\frac{2}{10}\)

\(\frac{2}{5};\frac{9}{20};\frac{1}{10}\)là những phân số bé hơn \(\frac{1}{2}\)

Chúc bạn học giỏi nha!!!

K cho mik vs nhé

Cách giải

X = 8/9 / ( 1+1/3+1/6+1/10+1/15+1/21)

1+1/3=4/3

4/3+1/6=3/2

3/2+1/10=8/5

8/5+1/15=5/3

5/3+1/21=12/7

4/3+3/2=17/6

8/5+5/3=49/15

(17/6+49/15)+17/6=183/30+17/6=286/30

8/9:286/30=2288/270=1140/135=228/27=76/9

X = 76/9

1. \(\frac{14}{45}=\frac{1}{9}+\frac{1}{5}\)

2. \(\left(1-\frac{1}{12}\right).\left(1-\frac{1}{11}\right).\left(1-\frac{1}{10}\right).\left(1-\frac{1}{9}\right).\left(1-\frac{1}{8}\right)\)

\(=\frac{11}{12}.\frac{10}{11}.\frac{9}{10}.\frac{8}{9}.\frac{7}{8}\)

Triệt tử với mẫu:

\(=\frac{7}{12}\)

1.ket qua la 1/5+1/9

2.=11/12x10/11x9/10x8/9x7/8

   =(11x10x9x8x7)/(12x11x10x9x8)

   =7/12