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8 tháng 3 2017

a=3/4*7/6=1/2+1/3=5/6

b=5/3*9/15=1-1/5=4/5

c=1/4*1/5=1/20:1/3=3/20

d=7/9:14/15=5/6*1/2=5/12

8 tháng 3 2017

Bài 1

a 2/5+3/6=12/30+15/30=27/30=9/10 .

b 5/9-1/6=30/54-9/54=21/54=7/18

5 tháng 3 2017

a) \(\frac{1}{5}:\frac{2}{15}=\frac{1}{5}\times\frac{15}{2}\) 

                  \(=\frac{15}{10}=\frac{3}{2}\)

b)\(\frac{3}{7}:\frac{9}{14}=\frac{3}{7}\times\frac{14}{9}\)

                \(=\frac{42}{63}=\frac{2}{3}\)

c) \(\frac{7}{12}:\frac{21}{24}=\frac{7}{12}\times\frac{24}{21}\)

                    \(=\frac{168}{252}=\frac{2}{3}\)

d) \(\frac{9}{13}:\frac{27}{26}=\frac{9}{13}\times\frac{26}{27}\)

                   \(=\frac{234}{351}=\frac{2}{3}\)

k nha

5 tháng 3 2017

A/ 15/10 = 3/2

B/ 42/63 = 2/3

C/ 168/252 = 2/3

D/ 234/351 = 2/3

9 tháng 3 2017

a) \(5+\frac{1}{4}=\frac{20}{4}+\frac{1}{4}=\frac{21}{4}\)

b) \(7-\frac{3}{5}=\frac{35}{5}-\frac{3}{5}=\frac{32}{5}\)

b) \(2\times\frac{9}{11}=\frac{18}{11}\)

d) \(\frac{2}{34}:5=\frac{2}{34}:\frac{5}{1}=\frac{2}{34}\times\frac{1}{5}=\frac{2}{170}=\frac{1}{85}\)

ủng hộ nha.

5 tháng 3 2017

a) 3/5:3/4=3/5x4/3=(3x4)/(5x3)=12/15=4/5

b)2/5:3/10=2/5x10/3=(2x10)/(5x3)=20/15=4/3

c)9/8:3/4=9/8x4/3=(9x4)/(8x3)=36/32=9/8

d)1/4:1/2=1/4x2=2/4=1/2

e)1/8:1/6=1/8x6=6/8=3/4

g)1/5:1/10=1/5x10=10/5=2

5 tháng 3 2017

a) 3/5 : 3/4 = 4/5

b) 2/5 : 3/10 = 4/3

c) 9/8 : 3/4 = 3/2

d)  1/4 : 1/2 = 1/2

e) 1/8 : 1/6 = 3/4

g) 1/5 : 1/10 = 2

tk tớ nha

a: \(\dfrac{16}{15}\cdot\dfrac{-5}{14}\cdot\dfrac{54}{24}\cdot\dfrac{56}{21}\)

\(=\dfrac{16}{24}\cdot\dfrac{-5}{15}\cdot\dfrac{54}{21}\cdot\dfrac{56}{14}\)

\(=\dfrac{2}{3}\cdot\dfrac{-1}{3}\cdot\dfrac{18}{7}\cdot4\)

\(=\dfrac{-2\cdot2\cdot4}{7}=-\dfrac{16}{7}\)

b: \(\dfrac{7}{3}\cdot\dfrac{-5}{2}\cdot\dfrac{15}{21}\cdot\dfrac{4}{-5}\)

\(=\dfrac{7}{3}\cdot\dfrac{5}{7}\cdot\dfrac{5}{2}\cdot\dfrac{4}{5}\)

\(=\dfrac{5}{3}\cdot\dfrac{4}{2}=\dfrac{5}{3}\cdot2=\dfrac{10}{3}\)

c: \(\left(-\dfrac{2}{5}+\dfrac{1}{3}\right)\left(\dfrac{3}{2}-\dfrac{3}{7}\right)\)

\(=\dfrac{-2\cdot5+3}{15}\cdot\dfrac{3\cdot7-3\cdot2}{14}\)

\(=\dfrac{-7}{15}\cdot\dfrac{15}{14}=\dfrac{-7}{14}=-\dfrac{1}{2}\)

d: \(\left(\dfrac{1}{2}-\dfrac{1}{3}\right)\left(5-\dfrac{1}{4}\right)\)

\(=\dfrac{3-2}{6}\cdot\dfrac{20-1}{4}\)

\(=\dfrac{1}{6}\cdot\dfrac{19}{4}=\dfrac{19}{24}\)

e: \(\left(\dfrac{4}{5}\right)^2=\dfrac{4^2}{5^2}=\dfrac{16}{25}\)

Giải:

a) \(2\dfrac{17}{20}-1\dfrac{15}{11}+6\dfrac{9}{20}:3\)

\(=\dfrac{57}{20}-\dfrac{26}{11}+\dfrac{129}{20}:3\) 

\(=\dfrac{107}{220}+\dfrac{43}{20}\)

\(=\dfrac{29}{11}\)

b) \(4\dfrac{3}{7}:\left(\dfrac{7}{5}.4\dfrac{3}{7}\right)\) 

\(=\dfrac{31}{7}:\left(\dfrac{7}{5}.\dfrac{31}{7}\right)\) 

\(=\dfrac{31}{7}:\dfrac{31}{5}\) 

\(=\dfrac{5}{7}\) 

c) \(\left(3\dfrac{2}{9}.\dfrac{15}{23}.1\dfrac{7}{29}\right):\dfrac{5}{23}\) 

\(=\left(\dfrac{29}{9}.\dfrac{15}{23}.\dfrac{36}{29}\right):\dfrac{5}{23}\) 

\(=\dfrac{60}{23}:\dfrac{5}{23}\) 

\(=12\)

26 tháng 12 2017

1=2:2+2-2

2=2:2+2:2

3=2*2-2:2

4=2*2*2:2

5=2*2+2:2

6=2*2*2-2

7=???????

8=2*2+2*2

9=???????

10=2*2*2+2

8 tháng 3 2017

Tính 

a ) 5/2 x 1/3 + 1/4

= 5/5+1/4

=13/12

b)5/2 +  1/3 x 1/4

= 5/2 + 1/12

= 31/12

c ) 5/2 -1/3 :1/4

= 5/2  - 4/3

= 7/6

tk mk nha ( nếu đúng )

hihi mơn nha !!!!!!!!!!

8 tháng 3 2017

a. = (5/2x2/3) +1/4

    = 5/3+1/4= 23/12

b. = 5/2+( 1/3x1/4)

    = 5/2+1/12

    =31/12

c. =5/2-( 1/3:1/4)

    = 5/2-4/3

    = 7/6

6 tháng 3 2017

A)2/7:4/5=2/7*5/4=10/28=5/14

b)3/8:9/4=3/8*4/9=12/72=1/6

c)8/21:4/7=8/21*7/4=56/84=2/3

D)5/8:15/8=5/8*8/15=40/120=1/3

k nha