-$\dfrac{4}{7}$ $\dfrac{15}{4}$-($\dfrac{11}{4}$ $\dfrac{3}{7} \dfrac{1}{2}-\dfrac{1}{3}$) $\dfrac{1}{5}\left(\dfrac{1}{2}-\dfrac{1}{3}\right):\left(\dfrac{-9}{10}\right) \dfrac{-7}{3}$ \(...

0

QN

Quỳnh nga

11 tháng 4 2022

Thực hiện các phép tính:

a,$\left(6\dfrac{4}{9}+\dfrac{7}{11}\right)-\left(4\dfrac{4}{9}-2\dfrac{4}{11}\right)$

b, $10\dfrac{1}{5}-5\dfrac{1}{2}.\dfrac{60}{11}+3:15\%$

c. $4\dfrac{3}{4}+\left(-0,37\right)+\dfrac{1}{8}+\left(-1,8\right)+\left(-2,5\right)+3\dfrac{1}{12}$

1

DC

dâu cute

11 tháng 4 2022

a, = (58/9 + 7/11) - (40/9 - 26/11)

= 701/99 - 206/99

= 5

b, = 51/5 - 11/2 . 60/11 + 3 : 3/20

= 51/5 - 30 + 20

= -99/5 + 20

= 1/5

c, = 19/4 + (-0,37) + 1/8 + (-1,8) + (-2,5) + 37/12

= 219/50 + -67/40 + 7/12

= 1973/600

Đúng(1)

C

ミ★ċậȗ✎ɞé✎ċá✎ṭíṅһ✎

1 tháng 3 2022

$\dfrac{-2}{7}-\dfrac{1}{4}$

$\dfrac{-1}{2}.\dfrac{4}{9}+\dfrac{3}{7}\div\dfrac{15}{14}$

$\left(\dfrac{-3}{4}+\dfrac{7}{10}\right)\div\left(\dfrac{-1}{5}\right)-\dfrac{2}{9}$

2

NL

Nguyễn Lê Phước Thịnh

1 tháng 3 2022

a: =-8/28-7/28=-15/28

b: $=\dfrac{-4}{18}+\dfrac{3}{7}\cdot\dfrac{14}{15}=\dfrac{-2}{9}+\dfrac{14}{15}=\dfrac{-10+42}{45}=\dfrac{32}{45}$

c: $=\dfrac{-3\cdot5+7\cdot2}{20}\cdot\dfrac{-5}{1}-\dfrac{2}{9}$

$=\dfrac{-7}{4}-\dfrac{2}{9}=\dfrac{-63}{36}-\dfrac{8}{36}=-\dfrac{71}{36}$

Thực hiện phép tính: a) $11\dfrac{3}{4}-\left(6\dfrac{5}{6}-4\dfrac{1}{2}\right)+1\dfrac{2}{3}$ b) $2\dfrac{17}{20}-1\dfrac{11}{15}+6\dfrac{9}{20}:3$ ...

R

Rhider

1 tháng 3 2022

$a,\dfrac{-2}{7}-\dfrac{1}{4}$

$=\dfrac{-8}{28}-\dfrac{7}{28}$

$=\dfrac{-15}{28}$

$b,\dfrac{-1}{2}.\dfrac{4}{9}+\dfrac{3}{7}\div\dfrac{15}{14}$

Đúng(1)

TT

Trần Thị Thảo

21 tháng 4 2022

1

NL

Nguyễn Lê Phước Thịnh

27 tháng 6 2023

a: =11+3/4-6-5/6+4+1/2+1+2/3

=10+9/12-10/12+6/12+8/12

=10+13/12=133/12

b: $=2+\dfrac{17}{20}-1-\dfrac{11}{15}+2+\dfrac{3}{20}$

=3-11/15

=34/15

c: $=\dfrac{31}{7}:\left(\dfrac{7}{5}\cdot\dfrac{31}{7}\right)$

$=\dfrac{31}{7}:\dfrac{31}{5}=\dfrac{5}{7}$

d: $=\dfrac{29}{8}\cdot\dfrac{36}{29}\cdot\dfrac{15}{23}\cdot\dfrac{23}{5}=\dfrac{9}{2}\cdot3=\dfrac{27}{2}$

DD

Đỗ Diệu Linh

13 tháng 9 2017

Tinh

$\dfrac{\left(1+2+3+...+100\right)\left(\dfrac{1}{3}-\dfrac{1}{5}-\dfrac{1}{7}-\dfrac{1}{9}\right)\left(6,3.12-21.36\right)}{\dfrac{1}{2}+\dfrac{1}{3}+\dfrac{1}{4}+...+\dfrac{1}{100}}$

$\dfrac{\left(\dfrac{3}{10}-\dfrac{4}{15}-\dfrac{7}{20}\right).\dfrac{5}{9}}{\left(\dfrac{1}{14}+\dfrac{1}{7}-\dfrac{-3}{35}\right)\dfrac{-4}{3}}$

#Toán lớp 7

2

NT

Nguyễn Thanh Hằng

13 tháng 9 2017

a/ $\dfrac{\left(1+2+.....+100\right)\left(\dfrac{1}{3}-\dfrac{1}{5}-\dfrac{1}{7}-\dfrac{1}{9}\right)\left(6,3.12-21.36\right)}{\dfrac{1}{2}+\dfrac{1}{3}+.......+\dfrac{1}{100}}$

$=\dfrac{\left(1+2+3+.....+100\right)\left(\dfrac{1}{3}-\dfrac{1}{5}-\dfrac{1}{7}-\dfrac{1}{9}\right).0}{\dfrac{1}{2}+\dfrac{1}{3}+.......+\dfrac{1}{100}}$

$=\dfrac{0}{\dfrac{1}{2}+\dfrac{1}{3}+.....+\dfrac{1}{100}}$

$=0$

TT

Trần Thị Hương

13 tháng 9 2017

bn có chép sai đề bài ko vậy

Tính giá trị biểu thức : 1. $A=\dfrac{\dfrac{2}{5}+\dfrac{2}{7}-\dfrac{2}{9}-\dfrac{2}{11}}{\dfrac{4}{5}+\dfrac{4}{7}-\dfrac{4}{9}-\dfrac{4}{11}}$ 2. $B=\dfrac{1^2}{1\cdot2}\cdot\dfrac{2^2}{2\cdot3}\cdot\dfrac{3^2}{3\cdot4}\cdot\dfrac{4^2}{4\cdot5}$ 3. $C=\dfrac{2^2}{1\cdot3}\cdot\dfrac{3^2}{2\cdot4}\cdot\dfrac{4^2}{3\cdot5}\cdot\dfrac{5^2}{4\cdot6}\cdot\dfrac{5^2}{4\cdot6}$ 4. $D=\left(\dfrac{4}{5}-\dfrac{1}{6}\right)\cdot\left(\dfrac{2}{3}\cdot\dfrac{1}{4}\right)^2$ 5. Cho...

NV

Nguyễn Vũ Hoàng

27 tháng 11 2017

Tính giá trị biểu thức :

1. $A=\dfrac{\dfrac{2}{5}+\dfrac{2}{7}-\dfrac{2}{9}-\dfrac{2}{11}}{\dfrac{4}{5}+\dfrac{4}{7}-\dfrac{4}{9}-\dfrac{4}{11}}$

2. $B=\dfrac{1^2}{1\cdot2}\cdot\dfrac{2^2}{2\cdot3}\cdot\dfrac{3^2}{3\cdot4}\cdot\dfrac{4^2}{4\cdot5}$

3. $C=\dfrac{2^2}{1\cdot3}\cdot\dfrac{3^2}{2\cdot4}\cdot\dfrac{4^2}{3\cdot5}\cdot\dfrac{5^2}{4\cdot6}\cdot\dfrac{5^2}{4\cdot6}$

4. $D=\left(\dfrac{4}{5}-\dfrac{1}{6}\right)\cdot\left(\dfrac{2}{3}\cdot\dfrac{1}{4}\right)^2$

5. Cho $M=8\dfrac{2}{7}-\left(3\dfrac{4}{9}+4\dfrac{2}{7}\right)$ ; $N=\left(10\dfrac{2}{9}+2\dfrac{3}{5}\right)-6\dfrac{2}{9}$. Tính $P=M-N$

6. $E=10101\left(\dfrac{5}{111111}+\dfrac{5}{222222}-\dfrac{4}{3\cdot7\cdot11\cdot13\cdot37}\right)$

7. $F=\dfrac{\dfrac{1}{3}+\dfrac{1}{7}-\dfrac{1}{13}}{\dfrac{2}{3}+\dfrac{2}{7}-\dfrac{2}{13}}\cdot\dfrac{\dfrac{3}{4}-\dfrac{3}{16}-\dfrac{3}{256}+\dfrac{3}{64}}{1-\dfrac{1}{4}+\dfrac{1}{16}-\dfrac{1}{64}}+\dfrac{5}{8}$

8. $G=\text{[}\dfrac{\left(6-4\dfrac{1}{2}\right):0,03}{\left(3\dfrac{1}{20}-2,65\right)\cdot4+\dfrac{2}{5}}-\dfrac{\left(0,3-\dfrac{3}{20}\right)\cdot1\dfrac{1}{2}}{\left(1,88+2\dfrac{3}{25}\right)\cdot\dfrac{1}{80}}\text{]}:\dfrac{49}{60}$

9. $H=\dfrac{1}{1\cdot2\cdot3}+\dfrac{1}{2\cdot3\cdot4}+\dfrac{1}{4\cdot5\cdot6}+...+\dfrac{1}{98\cdot99\cdot100}$

10. $I=\dfrac{8}{9}\cdot\dfrac{15}{16}\cdot\dfrac{24}{25}\cdot...\cdot\dfrac{2499}{2500}$

11. $K=\left(-1\dfrac{1}{2}\right)\left(-1\dfrac{1}{3}\right)\left(-1\dfrac{1}{4}\right)...\left(-1\dfrac{1}{999}\right)$

12. $L=1\dfrac{1}{3}+1\dfrac{1}{8}+1\dfrac{1}{15}...$ (98 thừa số)

13. $M=-2+\dfrac{1}{-2+\dfrac{1}{-2+\dfrac{1}{-2+\dfrac{1}{3}}}}$

14. $N=\dfrac{155-\dfrac{10}{7}-\dfrac{5}{11}+\dfrac{5}{23}}{403-\dfrac{26}{7}-\dfrac{13}{11}+\dfrac{13}{23}}$

15. $P=\left(\dfrac{1}{4}-1\right)\left(\dfrac{1}{5}-1\right)...\left(\dfrac{1}{2001}-1\right)$

16. $Q=\left(\dfrac{1}{1\cdot2}+\dfrac{1}{3\cdot4}+\dfrac{1}{4\cdot5}+...+\dfrac{1}{2005\cdot2006}\right):\left(\dfrac{1}{1004\cdot2006}+\dfrac{1}{1005\cdot2005}+...+\dfrac{1}{2006\cdot1004}\right)$

2

QH

Quang Ho Si

27 tháng 11 2017

1. $A=\dfrac{2\left(\dfrac{1}{5}+\dfrac{1}{7}-\dfrac{1}{9}-\dfrac{1}{11}\right)}{4\left(\dfrac{1}{5}+\dfrac{1}{7}-\dfrac{1}{9}-\dfrac{1}{11}\right)}=\dfrac{2}{4}=\dfrac{1}{2}$

2. $B=\dfrac{1^2.2^2.3^2.4^2}{1.2^2.3^2.4^2.5}=\dfrac{1}{5}$

3.$C=\dfrac{2^2.3^2.\text{4^2.5^2}.5^2}{1.2^2.3^2.4^2.5.6^2}=\dfrac{125}{36}$

4.D=$D=\left(\dfrac{4}{5}-\dfrac{1}{6}\right).\dfrac{4}{9}.\dfrac{1}{16}=\dfrac{19}{30}.\dfrac{1}{36}=\dfrac{19}{1080}$

NA

Nguyễn Anh Quang

29 tháng 4 2022

hôi lì sít

$a,\dfrac{-8}{5}:\left(1+\dfrac{2}{3}\right)$ $b,\dfrac{7}{5}x\dfrac{15}{49}-\left(\dfrac{4}{5}+\dfrac{2}{3}\right):\dfrac{11}{5}$$c,\dfrac{1}{3}:\left(\dfrac{2}{9}-\dfrac{7}{8}\right)$ $d,\left(\dfrac{1}{6}-\dfrac{4}{5}\right):\dfrac{7}{5}$Giúp mik...

QN

quan nguyen hoang

13 tháng 2 2022

Bài 1: Thực hiện phép tính a) $\left(\dfrac{3}{8}+\dfrac{-3}{4}+\dfrac{7}{12}\right):\dfrac{5}{6}+\dfrac{1}{2}$ b) $\dfrac{1}{2}+\dfrac{3}{4}-\left(\dfrac{3}{4}-\dfrac{4}{5}\right)$ c)...

1

DD

Đinh Đức Anh

13 tháng 2 2022

A -$\dfrac{24}{25}$

B -$\dfrac{5}{21}$

C -$\dfrac{24}{47}$

D -$\dfrac{19}{42}$

tick cho mk

Đúng(2)

I

ILoveMath

13 tháng 2 2022

trả lời hẳn ra sao bạn cứ chỉ ghi kết quả thế

Đúng(1)

NN

no no

29 tháng 3 2017

2

PN

Phạm Ngân Hà

28 tháng 4 2017

Bài 1:

a) $\left(\dfrac{3}{8}+\dfrac{-3}{4}+\dfrac{7}{12}\right):\dfrac{5}{6}+\dfrac{1}{2}$

$=\left(\dfrac{9}{24}+\dfrac{-18}{24}+\dfrac{14}{24}\right):\dfrac{5}{6}+\dfrac{1}{2}$

$=\dfrac{5}{24}:\dfrac{5}{6}+\dfrac{1}{2}$

$=\dfrac{5}{24}.\dfrac{6}{5}+\dfrac{1}{2}$

$=\dfrac{1}{4}+\dfrac{1}{2}$

$=\dfrac{1}{4}+\dfrac{2}{4}$

$=\dfrac{3}{4}$

b) $\dfrac{1}{2}+\dfrac{3}{4}-\left(\dfrac{3}{4}-\dfrac{4}{5}\right)$

$=\dfrac{1}{2}+\dfrac{3}{4}-\dfrac{3}{4}+\dfrac{4}{5}$

$=\left(\dfrac{1}{2}+\dfrac{4}{5}\right)+\left(\dfrac{3}{4}-\dfrac{3}{4}\right)$

$=\dfrac{1}{2}+\dfrac{4}{5}$

$=\dfrac{5}{10}+\dfrac{8}{10}$

$=\dfrac{9}{5}$

c) $6\dfrac{5}{12}:2\dfrac{3}{4}+11\dfrac{1}{4}.\left(\dfrac{1}{3}+\dfrac{1}{5}\right)$

$=\dfrac{77}{12}:\dfrac{11}{4}+\dfrac{42}{4}.\left(\dfrac{1}{3}+\dfrac{1}{5}\right)$

$=\dfrac{77}{12}.\dfrac{4}{11}+\dfrac{42}{4}.\left(\dfrac{5}{15}+\dfrac{3}{15}\right)$

$=\dfrac{7}{3}+\dfrac{42}{4}.\dfrac{8}{15}$

$=\dfrac{7}{3}+\dfrac{14.2}{1.3}$

$=\dfrac{7}{3}+\dfrac{28}{3}$

$=\dfrac{35}{3}$

d) $\left(\dfrac{7}{8}-\dfrac{3}{4}\right).1\dfrac{1}{3}-\dfrac{2}{7}.\left(3,5\right)^2$

$=\left(\dfrac{7}{8}-\dfrac{6}{8}\right).\dfrac{4}{3}-\dfrac{2}{7}.12\dfrac{1}{4}$

$=\dfrac{1}{8}.\dfrac{4}{3}-\dfrac{2}{7}.\dfrac{49}{4}$

$=\dfrac{1}{6}-\dfrac{7}{2}$

$=\dfrac{1}{6}-\dfrac{21}{6}$

$=\dfrac{-10}{3}$

e) $\left(\dfrac{3}{5}+0,415-\dfrac{3}{200}\right).2\dfrac{2}{3}.0,25$

$=\left(\dfrac{3}{5}+\dfrac{83}{200}-\dfrac{3}{200}\right).\dfrac{8}{3}.\dfrac{1}{4}$

$=\left(\dfrac{120}{200}+\dfrac{83}{200}-\dfrac{3}{200}\right).\dfrac{8}{3}.\dfrac{1}{4}$

$=1.\dfrac{8}{3}.\dfrac{1}{4}$

$=\dfrac{2}{3}$

f) $\dfrac{5}{16}:0,125-\left(2\dfrac{1}{4}-0,6\right).\dfrac{10}{11}$

$=\dfrac{5}{16}:\dfrac{1}{8}-\left(\dfrac{9}{4}-\dfrac{3}{5}\right).\dfrac{10}{11}$

$=\dfrac{5}{16}.\dfrac{8}{1}-\left(\dfrac{45}{20}-\dfrac{12}{20}\right).\dfrac{10}{11}$

$=\dfrac{5}{2}-\dfrac{33}{20}.\dfrac{10}{11}$

$=\dfrac{5}{2}-\dfrac{3}{2}$

$=\dfrac{2}{2}=1$

g) $0,25:\left(10,3-9,8\right)-\dfrac{3}{4}$

$=\dfrac{1}{4}:\dfrac{1}{2}-\dfrac{3}{4}$

$=\dfrac{1}{4}.\dfrac{2}{1}-\dfrac{3}{4}$

$=\dfrac{1}{2}-\dfrac{3}{4}$

$=\dfrac{2}{4}-\dfrac{3}{4}$

$=\dfrac{-1}{4}$

h) $1\dfrac{13}{15}.0,75-\left(\dfrac{11}{20}+20\%\right):\dfrac{7}{3}$

$=\dfrac{28}{15}.\dfrac{3}{4}-\left(\dfrac{11}{20}+\dfrac{1}{5}\right):\dfrac{7}{3}$

$=\dfrac{7}{5}-\left(\dfrac{11}{20}+\dfrac{4}{20}\right):\dfrac{7}{3}$

$=\dfrac{7}{5}-\dfrac{3}{4}:\dfrac{7}{3}$

$=\dfrac{7}{5}-\dfrac{9}{28}$

$=\dfrac{196}{140}-\dfrac{45}{140}$

$=\dfrac{151}{140}$

i) $\dfrac{\left(\dfrac{1}{2-0,75}\right).\left(0,2-\dfrac{2}{5}\right)}{\dfrac{5}{9}-1\dfrac{1}{12}}$

$=\dfrac{\left(\dfrac{1}{1,25}\right).\left(\dfrac{1}{5}-\dfrac{2}{5}\right)}{\dfrac{5}{9}-\dfrac{13}{12}}$

$=\dfrac{\dfrac{1}{1,25}.\dfrac{-1}{5}}{\dfrac{20}{36}-\dfrac{39}{36}}$

$=\dfrac{\dfrac{-1}{6,25}}{\dfrac{-19}{36}}$

k) $\dfrac{\dfrac{2}{3}+\dfrac{2}{7}-\dfrac{1}{14}}{-1-\dfrac{3}{7}+\dfrac{3}{28}}$

$=\dfrac{\dfrac{2}{3}+\dfrac{2}{7}-\dfrac{2}{28}}{-\dfrac{3}{3}-\dfrac{3}{7}+\dfrac{3}{28}}$

$=\dfrac{2\left(\dfrac{1}{3}+\dfrac{1}{7}-\dfrac{1}{28}\right)}{\left(-3\right)\left(\dfrac{1}{3}+\dfrac{1}{7}-\dfrac{1}{28}\right)}$

$=-\dfrac{2}{3}$

PN

Phạm Ngân Hà

29 tháng 4 2017

$A=0,7.2\dfrac{2}{3}.20.0,375.\dfrac{5}{28}$

$A=\dfrac{7}{10}.\dfrac{8}{3}.20.\dfrac{3}{8}.\dfrac{5}{28}$

$A=\left(\dfrac{7}{10}.\dfrac{5}{28}\right).\left(\dfrac{8}{3}.\dfrac{3}{8}\right).20$

$A=\dfrac{1}{8}.1.20$

$A=\dfrac{20}{8}=\dfrac{5}{2}$

$B=\left(9\dfrac{30303}{80808}+7\dfrac{303030}{484848}\right)+4,03$

$B=\left(9\dfrac{3}{8}+7\dfrac{5}{8}\right)+4,03$

$B=\left[\left(9+7\right)+\left(\dfrac{3}{8}+\dfrac{5}{8}\right)\right]+4,03$

$B=\left(16+1\right)+4,03$

$B=17+4,03$

$B=21,03$

$C=\left(9,75.21\dfrac{3}{7}+\dfrac{39}{4}.18\dfrac{4}{7}\right).\dfrac{15}{78}$

$C=\left(\dfrac{39}{4}.\dfrac{150}{7}+\dfrac{39}{4}.\dfrac{130}{7}\right).\dfrac{15}{78}$

$C=\dfrac{39}{4}.\left(\dfrac{150}{7}+\dfrac{130}{7}\right).\dfrac{15}{78}$

$C=\dfrac{39}{4}.40.\dfrac{15}{78}$

$C=390.\dfrac{15}{78}$

$C=75$

Tính giá trí của biểu thức sau theo cách hợp lí nhất. a) $\mathrm{A}=\dfrac{3}{5} \cdot \dfrac{6}{7}+\dfrac{3}{7}: \dfrac{5}{3}-\dfrac{2}{7}: 1 \dfrac{2}{3}$; b) $\mathrm{B}=\left(-13 \cdot \dfrac{2}{5}+\dfrac{-2}{9}: 2 \dfrac{1}{2}+\dfrac{2}{5}. \dfrac{11}{9}\right) \cdot 2 \dfrac{1}{2}$; c) $\mathrm{C}=\left(\dfrac{-4}{5}+\dfrac{5}{7}\right): \dfrac{2}{3}+\left(\dfrac{-1}{5}+\dfrac{2}{7}\right): \dfrac{2}{3}$; d)...

TD

Thầy Đức Anh

Giáo viên VIP

27 tháng 4 2022

#Toán lớp 7

14

PT

Phạm Trường Giang

VIP

22 tháng 6 2022

a) $A = \frac{3}{5} . \frac{6}{7} + \frac{3}{7} . \frac{3}{5} - \frac{2}{7} . \frac{3}{5}$
$= \frac{3}{5} \cdot (\frac{6}{7} + \frac{3}{7} - \frac{2}{7}) = \frac{3}{5}$
b) $B = (- 13 \cdot \frac{2}{5} + \frac{- 2}{9} \cdot \frac{2}{5} + \frac{2}{5} \cdot \frac{11}{9}) \cdot \frac{5}{2}$
$= (- 13 - \frac{2}{9} + \frac{11}{9}) \cdot \frac{2}{5} \cdot \frac{5}{2} = - 13 + (\frac{11}{9} - \frac{2}{9}) = - 12 .$
c) $C = (\frac{- 4}{5} + \frac{5}{7}) \cdot \frac{3}{2} + (\frac{- 1}{5} + \frac{2}{7}) \cdot \frac{3}{2} = (\frac{- 4}{5} + \frac{5}{7} + \frac{- 1}{5} + \frac{2}{7}) \cdot \frac{3}{2} = ((\frac{- 4}{5} + \frac{- 1}{5}) + (\frac{5}{7} + \frac{2}{7})) \cdot \frac{3}{2} = 0 .$
d) $D = \frac{4}{9} : (\frac{1}{15} - \frac{10}{15}) + \frac{4}{9} : (\frac{2}{22} - \frac{5}{22})$
$= \frac{4}{9} : \frac{- 3}{5} + \frac{4}{9} : \frac{- 3}{22} = \frac{4}{9} \cdot \frac{- 5}{3} + \frac{4}{9} . \frac{- 22}{3}$
$= \frac{4}{9} \cdot (\frac{- 5}{3} + \frac{- 22}{3}) = \frac{4}{9} . \frac{- 27}{3} = - 4 .$

T

TINH

13 tháng 7 2022

a) $\mathrm{A}=\dfrac{3}{5}. \dfrac{6}{7}+\dfrac{3}{7}. \dfrac{3}{5}-\dfrac{2}{7}. \dfrac{3}{5}$

b) $\mathrm{B} =\left(-13 \cdot \dfrac{2}{5}+\dfrac{-2}{9} \cdot \dfrac{2}{5}+\dfrac{2}{5} \cdot \dfrac{11}{9}\right) \cdot \dfrac{5}{2}$
$=\left(-13-\dfrac{2}{9}+\dfrac{11}{9}\right) \cdot \dfrac{2}{5} \cdot \dfrac{5}{2}=-13+\left(\dfrac{11}{9}-\dfrac{2}{9}\right)=-12 .$
c) $\mathrm{C} =\left(\dfrac{-4}{5}+\dfrac{5}{7}\right) \cdot \dfrac{3}{2}+\left(\dfrac{-1}{5}+\dfrac{2}{7}\right) \cdot \dfrac{3}{2} =\left(\dfrac{-4}{5}+\dfrac{5}{7}+\dfrac{-1}{5}+\dfrac{2}{7}\right) \cdot \dfrac{3}{2}=\left(\left(\dfrac{-4}{5}+\dfrac{-1}{5}\right)+\left(\dfrac{5}{7}+\dfrac{2}{7}\right)\right) \cdot \dfrac{3}{2}=0 .$
d) $\mathrm{D}=\dfrac{4}{9}:\left(\dfrac{1}{15}-\dfrac{10}{15}\right)+\dfrac{4}{9}:\left(\dfrac{2}{22}-\dfrac{5}{22}\right)$

SG

Sách Giáo Khoa

8 tháng 4 2017

Tính :
a) $\left(\dfrac{-2}{3}+\dfrac{3}{7}\right):\dfrac{4}{5}+\left(\dfrac{-1}{3}+\dfrac{4}{7}\right):\dfrac{4}{5}$
b) $\dfrac{5}{9}:\left(\dfrac{1}{11}-\dfrac{5}{22}\right)+\dfrac{5}{9}:\left(\dfrac{1}{15}-\dfrac{2}{3}\right).$

#Toán lớp 7

3

TT

Thien Tu Borum

8 tháng 4 2017

a) $(\frac{-2}{3} + \frac{3}{7}): \frac{4}{5} + (\frac{-1}{3} + \frac{4}{7}) : \frac{4}{5}$

= $(\frac{-2}{3}+ \frac{3}{7}+ \frac{-1}{3} +\frac{4}{7}):\frac{4}{5} = (\frac{-3}{3} +\frac{7}{7}): \frac{4}{5} = (-1+1):\frac{4}{5} = 0$

b) $\frac{5}{9}: (\frac{1}{11} - \frac{5}{22}) + \frac{5}{9} :(\frac{1}{15} - \frac{2}{3})$ = $\frac{5}{9}: \frac{2 - 5}{22} + \frac{5}{9}: \frac{1-10}{15} = \frac{5}{9}.\frac{22}{-3}+\frac{5}{9}.\frac{15}{-9} = \frac{5}{9}(\frac{22}{-3} + \frac{15}{-9})=\frac{5}{9}.\frac{-27}{3}= 5.(-1)=-5$

TN

Trần Nhật Minh

9 tháng 4 2017

a, $\left(\dfrac{-2}{3}+\dfrac{3}{7}\right)-\dfrac{5}{21}:\dfrac{4}{5}+\left(\dfrac{-1}{3}+\dfrac{4}{7}\right):\dfrac{4}{5}\\ = -\dfrac{5}{21}:\dfrac{4}{5}+ \left(-\dfrac{5}{21}\right):\dfrac{4}{5}\\ =\left[-\dfrac{5}{21}+\left(-\dfrac{5}{21}\right)\right]:\dfrac{4}{5}\\ -\dfrac{10}{21}:\dfrac{4}{5}\\ =-\dfrac{25}{42}$

b,

$\dfrac{5}{9}:\left(\dfrac{1}{11}-\dfrac{5}{22}\right)+\dfrac{5}{9}:\left(\dfrac{1}{15}-\dfrac{2}{3}\right)\\ =\dfrac{5}{9}:\dfrac{-3}{22}+\dfrac{5}{9}:-\dfrac{3}{5}\\ =\dfrac{5}{9}:\left(\dfrac{-3}{22}+-\dfrac{3}{5}\right)\\ =\dfrac{5}{9}:-\dfrac{81}{110}\\ =-\dfrac{550}{729}$