Tính nhanh: a)A=(19\(\dfrac{5}{8}\):\(\dfrac{7}{12}\)-13\(\dfrac{1}{4}\):\(\dfrac{7}{2}\))x\(\dfrac{4}{5}\) b)B=(9\(\dfrac{30303}{80808}\) 7\(\dfrac{303030}{808080}\)) 4.03 Tìm x: 5\(\dfrac{18}{17...

BT

Bình Trần Thị thanh

26 tháng 4 2017

Tính nhanh: a)A=(19\(\dfrac{5}{8}\):\(\dfrac{7}{12}\)-13\(\dfrac{1}{4}\):\(\dfrac{7}{2}\))x\(\dfrac{4}{5}\) b)B=(9\(\dfrac{30303}{80808}\)+7\(\dfrac{303030}{808080}\))+4.03 Tìm x: 5\(\dfrac{18}{17}\): x+(-\(\dfrac{4}{17}\)) : x + \(3\dfrac{1}{7}\):\(17\dfrac{1}{3}\)=\(\dfrac{4}{11}\) Mấy bạn ơi cố giúp mik nha ai xong đầu mik tích hộ...

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#Toán lớp 6

3

BT

Bình Trần Thị thanh

6 tháng 5 2017

giúp mik đi năn nỉ đó

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QN

Quach Ngoc Dieu

8 tháng 5 2017

dễ mà

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L

lqhiuu

4 tháng 6 2017

bài 1: TÍNH HỢP LÝ

a, \(49\dfrac{8}{23}-\left(5\dfrac{7}{32}+14\dfrac{8}{23}\right)\)

b, \(-\dfrac{3}{7}.\dfrac{5}{9}+\dfrac{4}{9}.\dfrac{-3}{7}+2\dfrac{3}{7}\)

c, \(0,7.2\dfrac{2}{3}.20.0.375.\dfrac{5}{28}\)

d, \(\left(9\dfrac{30303}{80808}+7\dfrac{303030}{484848}\right)+4.03\)

#Toán lớp 6

2

Q

qwerty

4 tháng 6 2017

a) \(49\dfrac{8}{23}-\left(5\dfrac{7}{32}+14\dfrac{8}{23}\right)\)

\(=\dfrac{1135}{23}-\left(\left(5+14\right)+\left(\dfrac{7}{32}+\dfrac{8}{23}\right)\right)\)

\(=\dfrac{1135}{23}-\left(19+\dfrac{417}{736}\right)\)

\(=\dfrac{1135}{23}-19\dfrac{417}{736}\)

\(=\dfrac{1135}{23}-\dfrac{14401}{736}\)

\(=\dfrac{953}{32}\)

b) \(-\dfrac{3}{7}\cdot\dfrac{5}{9}+\dfrac{4}{9}\cdot\dfrac{-3}{7}+2\dfrac{3}{7}\)

\(=-\dfrac{1}{7}\cdot\dfrac{5}{3}-\dfrac{4}{3}\cdot\dfrac{1}{7}+\dfrac{17}{7}\)

\(=-\dfrac{5}{21}-\dfrac{4}{21}+\dfrac{17}{7}\)

\(=2\)

c) \(0,7\cdot2\dfrac{2}{3}\cdot20\cdot0,375\cdot\dfrac{5}{28}\)

\(=\dfrac{7}{10}\cdot\dfrac{8}{3}\cdot20\cdot\dfrac{3}{8}\cdot\dfrac{5}{28}\)

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

\(=\dfrac{5}{2}\)

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

\(=\left(9\cdot\dfrac{3}{8}+\dfrac{303030}{69264}\right)+\dfrac{403}{100}\)

\(=\left(\dfrac{27}{8}+\dfrac{35}{8}\right)+\dfrac{403}{100}\)

\(=\dfrac{31}{4}+\dfrac{403}{100}\)

\(=\dfrac{589}{50}\)

P/s: Đánh dấu phẩy, dấu chấm (dấu nhân) cần rõ ràng (vì dấu chấm người ta sẽ hiểu là dấu nhân thay vì hiểu là dấu phẩy)

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LN

Lam Nguyễn

5 tháng 6 2017

a) \(49\dfrac{8}{23}\)- \(\left(5\dfrac{7}{32}+14\dfrac{8}{23}\right)\)

= \(\left(49\dfrac{8}{23}-14\dfrac{8}{23}\right)+5\dfrac{7}{32}\)

=35+\(5\dfrac{7}{32}\)

=\(\dfrac{1287}{32}\)

b)\(-\dfrac{3}{7}.\dfrac{5}{9}+\dfrac{4}{9}.\dfrac{-3}{7}+2\dfrac{3}{7}\)

=\(\left[\left(\dfrac{-3}{7}\right).\left(\dfrac{5}{9}+\dfrac{4}{9}\right)\right]+2\dfrac{3}{7}\)

=\(\left[\left(\dfrac{-3}{7}\right).\dfrac{9}{9}\right]+2\dfrac{3}{7}\)

=\(\left[\left(\dfrac{-3}{7}\right).1\right]+2\dfrac{3}{7}\)

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

=2

c) 0,7.\(2\dfrac{2}{3}\).20.0.375.\(\dfrac{5}{28}\)

=0 (Vì có một thừ số là 0 nên nguyên cả tích là 0)

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

=17+4,03

=21,03

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XT

Xuân Tuyền Đặng

28 tháng 3 2022

...

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#Toán lớp 5

2

XT

Xuân Tuyền Đặng

28 tháng 3 2022

ai giúp mik ik T_T

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NT

Nguyễn Thị Thương Hoài

Giáo viên VIP

5 tháng 8 2023

a, \(\dfrac{7}{8}\) \(\times\) \(\dfrac{3}{13}\) + \(\dfrac{4}{9}\) \(\times\) \(\dfrac{4}{13}\)

= \(\dfrac{1}{13}\) \(\times\)( \(\dfrac{21}{8}\) + \(\dfrac{16}{9}\))

= \(\dfrac{1}{13}\) \(\times\)( \(\dfrac{189}{72}\) + \(\dfrac{128}{72}\))

= \(\dfrac{1}{13}\) \(\times\) \(\dfrac{317}{73}\)

= \(\dfrac{317}{949}\)

b, \(\dfrac{6}{5}\) + \(\dfrac{7}{3}\) + \(\dfrac{8}{9}\)

= \(\dfrac{54}{45}\) + \(\dfrac{105}{45}\) + \(\dfrac{40}{45}\)

= \(\dfrac{199}{45}\)

c, 23 : \(\dfrac{5}{14}\) + \(\dfrac{6}{7}\) + \(\dfrac{4}{9}\)

= \(\dfrac{322}{5}\) + \(\dfrac{6}{7}\) + \(\dfrac{4}{9}\)

= \(\dfrac{20286}{315}\) + \(\dfrac{270}{315}\) + \(\dfrac{140}{315}\)

= \(\dfrac{20696}{315}\)

d, 4\(\dfrac{1}{4}\) + 7\(\dfrac{3}{7}\) - 2\(\dfrac{4}{17}\)

= 4 + \(\dfrac{1}{4}\) + 7 + \(\dfrac{3}{7}\) - 2 - \(\dfrac{4}{17}\)

= (4+7-2) + (\(\dfrac{1}{4}\) + \(\dfrac{3}{7}\) - \(\dfrac{4}{17}\))

= 9 + \(\dfrac{119}{476}\) + \(\dfrac{204}{476}\) - \(\dfrac{112}{476}\)

= 9\(\dfrac{211}{476}\) = \(\dfrac{4495}{476}\)

e, 8 - (9\(\dfrac{2}{11}\) + \(\dfrac{8}{33}\))

= 8 - 9 - \(\dfrac{2}{11}\) - \(\dfrac{8}{33}\)

= -1 - \(\dfrac{2}{11}\) - \(\dfrac{8}{33}\)

= \(\dfrac{-33}{33}\) - \(\dfrac{-6}{33}\) - \(\dfrac{8}{33}\)

= - \(\dfrac{47}{33}\)

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NN

no no

29 tháng 3 2017

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)...

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#Toán lớp 6

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

\(=\dfrac{\dfrac{2}{3}+\dfrac{2}{7}-\dfrac{2}{28}}{-\dfrac{3}{3}-\dfrac{3}{7}+\dfrac{3}{28}}\)

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

\(=-\dfrac{2}{3}\)

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PN

Phạm Ngân Hà

29 tháng 4 2017

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

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

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

\(A=\dfrac{1}{8}.1.20\)

\(A=\dfrac{20}{8}=\dfrac{5}{2}\)

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

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

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

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

\(B=17+4,03\)

\(B=21,03\)

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

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

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

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

\(C=390.\dfrac{15}{78}\)

\(C=75\)

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MN

Minh Ngọc 5D - Tuệ Minh1G

24 tháng 3 2023

bài 1 tính :\(\dfrac{-8}{9}\) . \(\dfrac{12}{19}\) . \(\dfrac{9}{-4}\) . \(\dfrac{19}{24}\) \(\dfrac{-5}{16}\) . \(\dfrac{17}{15}\) : \(\dfrac{-17}{8}\) \(\dfrac{4}{13}\) . \(\dfrac{2}{7}\) + \(\dfrac{-3}{26}\) + \(\dfrac{4}{13}\) . \(\dfrac{5}{7}\) \(\dfrac{6}{11}\) . \(\dfrac{3}{4}\) + \(\dfrac{-12}{60}\) +\(\dfrac{-3}{4}\) ...

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#Toán lớp 6

2

MN

Minh Ngọc 5D - Tuệ Minh1G

24 tháng 3 2023

giúp mk vs mn ơi , mai cô giáo ktra mk r

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NL

Nguyễn Lê Phước Thịnh

24 tháng 3 2023

a: \(=\dfrac{8}{9}\cdot\dfrac{9}{4}\cdot\dfrac{12}{19}\cdot\dfrac{19}{24}=\dfrac{1}{2}\cdot2=1\)

b: \(=\dfrac{5}{16}\cdot\dfrac{17}{15}\cdot\dfrac{8}{17}=\dfrac{5}{16}\cdot\dfrac{8}{15}=\dfrac{40}{240}=\dfrac{1}{6}\)

c: \(=\dfrac{4}{13}\left(\dfrac{2}{7}+\dfrac{5}{7}\right)-\dfrac{3}{26}=\dfrac{4}{13}-\dfrac{3}{26}=\dfrac{5}{26}\)

c: \(=\dfrac{3}{4}\left(\dfrac{6}{11}+\dfrac{5}{11}\right)-\dfrac{1}{5}=\dfrac{3}{4}-\dfrac{1}{5}=\dfrac{11}{20}\)

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HN

Hang Nguyen

22 tháng 7 2021

bài 3 thực hiện phép tínha\(\dfrac{5}{8}+\dfrac{3}{17}+\dfrac{4}{18}+\dfrac{20}{-17}+\dfrac{-2}{9}+\dfrac{21}{56}\)b\(\left(\dfrac{9}{16}+\dfrac{8}{-27}\right)+\left(1+\dfrac{7}{16}+\dfrac{-19}{27}\right)\)c\(\left(\dfrac{13}{5}+\dfrac{7}{16}\right)+\left(\dfrac{-15}{16}+\dfrac{6}{15}\right)\) ...

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#Toán lớp 6

1

NL

Nguyễn Lê Phước Thịnh

22 tháng 7 2021

a) Ta có: \(\dfrac{5}{8}+\dfrac{3}{17}+\dfrac{4}{18}+\dfrac{20}{-17}+\dfrac{-2}{9}+\dfrac{21}{56}\)

\(=\left(\dfrac{3}{17}-\dfrac{20}{17}\right)+\left(\dfrac{2}{9}-\dfrac{2}{9}\right)+\left(\dfrac{5}{8}+\dfrac{3}{8}\right)\)

\(=-1+1=0\)

b) Ta có: \(\left(\dfrac{9}{16}+\dfrac{8}{-27}\right)+\left(1+\dfrac{7}{16}+\dfrac{-19}{27}\right)\)

\(=\left(\dfrac{9}{16}+\dfrac{7}{16}\right)+\left(\dfrac{-8}{27}-\dfrac{19}{27}\right)+1\)

=1-1+1=1

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HN

Hồ Ngọc Bảo Nam

22 tháng 7 2021

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PV

Phạm Vũ Hà My

15 tháng 11 2021

a) \(\dfrac{5}{7}\)+\(\dfrac{3}{4}\).\(\dfrac{-11}{2}\)b) (\(\dfrac{12}{17}\)+\(\dfrac{19}{7}\)) - (\(\dfrac{-5}{17}\)-\(\dfrac{3}{7}\))c)...

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#Toán lớp 7

1

NH

Nguyễn Hoàng Minh

15 tháng 11 2021

\(a,=\dfrac{5}{7}-\dfrac{33}{8}=-\dfrac{191}{56}\\ b,=\left(\dfrac{12}{17}+\dfrac{5}{17}\right)+\left(\dfrac{19}{7}+\dfrac{3}{7}\right)=1+3=4\\ c,=\left(0,125\cdot8\right)^{12}-\left(\dfrac{45}{15}\right)^3=1-3^3=-26\\ d,=\left(-\dfrac{1}{3}\right)\left(5\dfrac{2}{7}-2\dfrac{2}{7}\right)=-\dfrac{1}{3}\cdot3=-1\\ e,=\dfrac{3^4\cdot3^6}{3^9}=3\)

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PV

Phạm Vũ Hà My

15 tháng 11 2021

Thank you ^^

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NA

Ngọc Anh

13 tháng 3 2022

Bài 1 : thực hiện các phép tính ( tính hợp lí nếu có thể ):a ,\(\dfrac{7}{2}.\dfrac{8}{13}+\dfrac{8}{13}.\dfrac{-5}{2}+\dfrac{8}{13}\)b , \(\dfrac{-5}{17}.\dfrac{-9}{23}+\dfrac{9}{23}.\dfrac{-22}{17}+11\dfrac{9}{23}\)Bài 2 : tìm x , biết :a , \(\dfrac{7}{8}+x=\dfrac{3}{5}\)b...

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#Toán lớp 6

1

NH

Nguyễn Huy Tú

13 tháng 3 2022

Bài 2 :

a, \(x=\dfrac{3}{5}-\dfrac{7}{8}=\dfrac{24-30}{40}=-\dfrac{6}{40}=-\dfrac{3}{20}\)

b, \(2x-1=-2\Leftrightarrow x=-\dfrac{1}{2}\)

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M

mtruc.owo

1 tháng 7 2021

1.Tính \(a,5\text{x}\dfrac{7}{3}\) \(b,\dfrac{13}{4}:7\)2.Tính \(a,\dfrac{3}{7}+\dfrac{2}{5}+\dfrac{3}{4}\) \(b,\dfrac{9}{7}-\dfrac{5}{11}\text{x}\dfrac{11}{7}\) \(c,\dfrac{3}{5}\text{x}\dfrac{5}{7}\text{+}\dfrac{4}{7}\) \(d,\dfrac{7}{9}\text{x}\dfrac{2}{5}:\dfrac{3}{11}\) e,\(\dfrac{9}{7}+\dfrac{2}{3}-\dfrac{1}{4}\) g,\(\dfrac{4}{9}:\dfrac{3}{5}\text{x}\dfrac{2}{11}\) ...

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#Toán lớp 5

10

DT

Đinh Thị Trang Nhi

1 tháng 7 2021

\(a,5x\dfrac{7}{3}=\dfrac{5}{1}x\dfrac{7}{3}=\dfrac{35}{3};b,\dfrac{13}{4}:7=\dfrac{13}{4} :\dfrac{7}{1}=\dfrac{13}{4}x\dfrac{1}{7}=\dfrac{13}{28}\)

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H

Ħäńᾑïě🧡♏

1 tháng 7 2021

1. Tính

\(a,5\times\dfrac{7}{3}=\dfrac{35}{3}\)

\(b,\dfrac{13}{4}:7=\dfrac{13}{4}\times\dfrac{1}{7}=\dfrac{13}{28}\)

2. Tính

\(a,\dfrac{3}{7}+\dfrac{2}{5}+\dfrac{3}{4}\)

\(=\dfrac{15}{35}+\dfrac{14}{35}+\dfrac{3}{4}\)

\(=\dfrac{29}{35}+\dfrac{3}{4}\)

\(=\dfrac{116}{140}+\dfrac{105}{140}\)

\(=\dfrac{221}{140}\)

\(b,\dfrac{9}{7}-\dfrac{5}{11}\times\dfrac{11}{7}\)

\(=\dfrac{9}{7}-\dfrac{55}{77}\)

\(=\dfrac{99}{77}-\dfrac{55}{77}\)

\(=\dfrac{44}{77}=\dfrac{4}{7}\)

\(c,\dfrac{3}{5}\times\dfrac{5}{7}+\dfrac{4}{7}\)

\(=\dfrac{3}{5}\times\left(\dfrac{5}{7}+\dfrac{4}{7}\right)\)

\(=\dfrac{3}{5}\times\dfrac{9}{7}\)

\(=\dfrac{27}{35}\)

\(d,\dfrac{7}{9}\times\dfrac{2}{5}:\dfrac{3}{11}\)

\(=\dfrac{14}{45}:\dfrac{3}{11}\)

\(=\dfrac{14}{45}\times\dfrac{11}{3}\)

\(=\dfrac{154}{135}\)

\(e,\dfrac{9}{7}+\dfrac{2}{3}-\dfrac{1}{4}\)

\(=\dfrac{27}{21}+\dfrac{14}{21}-\dfrac{1}{4}\)

\(=\dfrac{41}{21}-\dfrac{1}{4}\)

\(=\dfrac{164}{84}-\dfrac{21}{84}\)

\(=\dfrac{143}{84}\)

\(g,\dfrac{4}{9}:\dfrac{3}{5}\times\dfrac{2}{11}\)

\(=\dfrac{4}{9}\times\dfrac{5}{3}\times\dfrac{2}{11}\)

\(=\dfrac{20}{27}\times\dfrac{2}{11}\)

\(=\dfrac{40}{297}\)

\(h,\dfrac{7}{2}-\dfrac{3}{10}:\dfrac{2}{5}\)

\(=\left(\dfrac{7}{2}-\dfrac{3}{10}\right):\dfrac{2}{5}\)

\(=\left(\dfrac{35}{10}-\dfrac{3}{10}\right):\dfrac{2}{5}\)

\(=\dfrac{32}{10}:\dfrac{2}{5}\)

\(=\dfrac{16}{5}\times\dfrac{5}{2}\)

\(=\dfrac{80}{10}=8\)

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LP

Lê Phương Linh

1 tháng 11 2023 - olm

Tìm x, biết: a) \(\dfrac{1}{20}\) - (x - \(\dfrac{8}{5}\)) = \(\dfrac{1}{10}\) b) \(\dfrac{7}{4}\) - (x + \(\dfrac{5}{3}\)) = \(\dfrac{-12}{5}\) c) x - [\(\dfrac{17}{2}\) - \(\left(\dfrac{-3}{7}+\dfrac{5}{3}\right)\)]...

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#Toán lớp 7

2

NT

Nguyễn Thùy Dương

1 tháng 11 2023

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KV

Kiều Vũ Linh

1 tháng 11 2023

a) 1/20 - (x - 8/5) = 1/10

x - 8/5 = 1/20 - 1/10

x - 8/5 = -1/20

x = -1/20 + 8/5

x = 31/20

b) 7/4 - (x + 5/3) = -12/5

x + 5/3 = 7/4 + 12/5

x + 5/3 = 83/20

x = 83/20 - 5/3

x = 149/60

c) x - [17/2 - (-3/7 + 5/3)] = -1/3

x - (17/2 - 26/21) = -1/3

x - 305/42 = -1/3

x = -1/3 + 305/42

x = 97/14

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