Tính hợp lí :A = $\dfrac{-2}{9}$ $\dfrac{-3}{4}$ $\dfrac{3}{5}$ $\dfrac{1}{15}$ $\dfrac{1}{57}$ $\dfrac{1}{3}$ $\dfrac{-1}{36}$B = $\dfrac{1}{2}$ $\dfrac{-1}{5}$ \(\d...

Tính (Tính hợp lí nếu có thể)a) $\dfrac{-7}{12}$-$\dfrac{3}{36}$b) (4-$\dfrac{5}{12}$):2+$\dfrac{5}{24}$c) $\dfrac{8}{9}$+$\dfrac{1}{9}$.$\dfrac{2}{13}$+$\dfrac{1}{9}$.$\dfrac{11}{13}$d) $\dfrac{3}{4}$.$\dfrac{8}{9}$.$\dfrac{15}{16}$. ... .$\dfrac{9999}{10000}$e) $\dfrac{3}{1.4}$+$\dfrac{3}{4.7}$+$\dfrac{3}{7.10}$+...+$\dfrac{3}{97.100}$*Lưu ý: Mong các anh chị trình bày chi tiết để em có thể hiểu bài, em xin các anh chị đừng viết...

#Toán lớp 5

0

AT

Anh Tuấn Đào

11 tháng 4 2022

1

NL

Nguyễn Lê Phước Thịnh

2 tháng 7 2023

a: =-21/36-3/36=-24/36=-2/3

b: =43/12*1/2+5/24=43/24+5/24=2

c: =8/9+1/9=1

e: =1-1/4+1/4-1/7+...+1/97-1/100

=1-1/100=99/100

LH

Ly Hoàng

25 tháng 7 2018

Tính nhanh :

$C=\dfrac{1}{3}+\dfrac{-3}{4}+\dfrac{3}{5}+\dfrac{1}{57}+\dfrac{-1}{36}+\dfrac{1}{15}+\dfrac{-2}{9}$

$D=\dfrac{1}{2}+\dfrac{-1}{5}+\dfrac{-5}{7}+\dfrac{1}{6}+\dfrac{-3}{35}+\dfrac{1}{3}+\dfrac{1}{41}$

$E=\dfrac{-1}{2}+\dfrac{3}{5}+\dfrac{-1}{9}+\dfrac{1}{127}+\dfrac{-7}{18}+\dfrac{4}{35}+\dfrac{2}{7}$

2

D

阮草~๖ۣۜDαɾƙ

17 tháng 8 2018

$D=\dfrac{1}{2}+\dfrac{-1}{5}+\dfrac{-5}{7}+\dfrac{1}{6}+\dfrac{-3}{35}+\dfrac{1}{3}+\dfrac{1}{41}$

$D=\left(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{3}\right)+\left(\dfrac{-1}{5}+\dfrac{-5}{7}+\dfrac{-3}{35}\right)+\dfrac{1}{41}$

$D=1+-1+\dfrac{1}{41}$

$D=0+\dfrac{1}{41}$

$D=\dfrac{1}{41}$

NL

Nguyễn Lê Phước Thịnh

22 tháng 8 2022

$C=\left(\dfrac{1}{3}+\dfrac{3}{5}+\dfrac{1}{15}\right)+\left(\dfrac{-3}{4}+\dfrac{-1}{36}+\dfrac{-2}{9}\right)+\dfrac{1}{57}$

$=\dfrac{5+9+1}{15}+\dfrac{-27-1-8}{36}+\dfrac{1}{57}$

=1/57

$E=\left(-\dfrac{1}{2}-\dfrac{1}{9}-\dfrac{7}{18}\right)+\left(\dfrac{3}{5}+\dfrac{4}{35}+\dfrac{2}{7}\right)+\dfrac{1}{127}=\dfrac{1}{127}$

YA

Yuuki Asuna

3 tháng 4 2017

Thực hiện phép tính sau bằng cách hợp lí nhất :

$\dfrac{1}{3}+\dfrac{-3}{4}+\dfrac{3}{5}+\dfrac{1}{57}+\dfrac{-1}{36}+\dfrac{1}{15}+\dfrac{-2}{9}$

1

NL

Nguyễn Lê Phước Thịnh

14 tháng 5 2022

$=\left(\dfrac{1}{3}+\dfrac{3}{5}+\dfrac{1}{15}\right)+\left(-\dfrac{3}{4}-\dfrac{1}{36}-\dfrac{2}{9}\right)+\dfrac{1}{57}$

$=\dfrac{5+9+1}{15}+\dfrac{-27-1-8}{36}+\dfrac{1}{57}=\dfrac{1}{57}$

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NT

nguyễn trần minh

16 tháng 9 2017

a) A= $\dfrac{1}{3}-\dfrac{3}{4}-\left(-\dfrac{3}{5}\right)+\dfrac{1}{72}-\dfrac{2}{9}-\dfrac{1}{36}+\dfrac{1}{15}$

b) B=$\dfrac{1}{5}-\dfrac{3}{7}+\dfrac{5}{9}-\dfrac{2}{9}+\dfrac{7}{13}-\dfrac{2}{11}-\dfrac{5}{9}+\dfrac{3}{7}-\dfrac{1}{5}$

c) C=$\dfrac{1}{100}-\dfrac{1}{100.99}-\dfrac{1}{99.98}-\dfrac{1}{98.97}-......-\dfrac{1}{3.2}-\dfrac{1}{2.1}$

1

QN

Quỳnh Như

16 tháng 9 2017

a) $A=\dfrac{1}{3}-\dfrac{3}{4}-\left(-\dfrac{3}{5}\right)+\dfrac{1}{72}-\dfrac{2}{9}-\dfrac{1}{36}+\dfrac{1}{15}$

$=\dfrac{1}{3}-\dfrac{3}{4}+\dfrac{3}{5}+\dfrac{1}{72}-\dfrac{2}{9}-\dfrac{1}{36}+\dfrac{1}{15}$

$=\left(\dfrac{1}{3}+\dfrac{3}{5}+\dfrac{1}{15}\right)-\left(\dfrac{3}{4}+\dfrac{2}{9}+\dfrac{1}{36}\right)+\dfrac{1}{72}$

$=\left(\dfrac{5}{15}+\dfrac{9}{15}+\dfrac{1}{15}\right)-\left(\dfrac{27}{36}+\dfrac{8}{36}+\dfrac{1}{36}\right)+\dfrac{1}{72}$

$=1-1+\dfrac{1}{72}$

$=0+\dfrac{1}{72}=\dfrac{1}{72}$

b) $B=\dfrac{1}{5}-\dfrac{3}{7}+\dfrac{5}{9}-\dfrac{2}{9}+\dfrac{7}{13}-\dfrac{2}{11}-\dfrac{5}{9}+\dfrac{3}{7}-\dfrac{1}{5}$

$=\left(\dfrac{1}{5}-\dfrac{1}{5}\right)+\left(-\dfrac{3}{7}+\dfrac{3}{7}\right)+\left(\dfrac{5}{9}-\dfrac{5}{9}\right)-\left(\dfrac{2}{9}-\dfrac{7}{13}+\dfrac{2}{11}\right)$

$=0+0+0-\left(\dfrac{286}{1287}-\dfrac{693}{1287}+\dfrac{234}{1287}\right)$

$=-\left(-\dfrac{173}{1287}\right)$

$=\dfrac{173}{1287}$

c) $C=\dfrac{1}{100}-\dfrac{1}{100.99}-\dfrac{1}{99.98}-.....-\dfrac{1}{3.2}-\dfrac{1}{2.1}$

$=\dfrac{1}{100}-\left(\dfrac{1}{100.99}+\dfrac{1}{99.98}+\dfrac{1}{98.97}+...+\dfrac{1}{3.2}+\dfrac{1}{2.1}\right)$

$=\dfrac{1}{100}-\left(\dfrac{1}{1.2}+\dfrac{1}{2.3}+...+\dfrac{1}{97.98}+\dfrac{1}{98.99}+\dfrac{1}{99.100}\right)$

$=\dfrac{1}{100}-\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+...+\dfrac{1}{97}-\dfrac{1}{98}+\dfrac{1}{98}-\dfrac{1}{99}+\dfrac{1}{99}-\dfrac{1}{100}\right)$

$=\dfrac{1}{100}-\left(1-\dfrac{1}{100}\right)$

$=\dfrac{-49}{50}$

➶➶➶ 𝕾𝖕𝖎𝖉𝖊𝖗 𝖒𝖆𝖓 ➷➷➷

26 tháng 5 2021

$\text{Thực hiện phép tính một cách hợp lí:}$

$\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{2}{15}:\dfrac{1}{5}+\dfrac{3}{5}.\dfrac{1}{3}$ $\left(4-\dfrac{5}{12}\right):2+\dfrac{5}{24}$

3

TT

😈tử thần😈

26 tháng 5 2021

$\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{2}{15}:\dfrac{1}{5}+\dfrac{3}{5}.\dfrac{1}{3}$

=$\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{2}{15}.\dfrac{5}{1}+\dfrac{3}{5}.\dfrac{1}{3}$

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

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

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

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TT

😈tử thần😈

26 tháng 5 2021

$\left(4-\dfrac{5}{12}\right):2+\dfrac{5}{24}$

=$\left(4-\dfrac{5}{12}\right).\dfrac{1}{2}+\dfrac{5}{24}$

=$4.\dfrac{1}{2}-\dfrac{5}{12}.\dfrac{1}{2}+\dfrac{5}{24}$

=$2-\dfrac{5}{24}+\dfrac{5}{24}=2$

HT

Hoàng Thúy An

19 tháng 9 2017

tinh nhanh

A=$\dfrac{1}{3}-\dfrac{3}{4}-\left(\dfrac{-3}{5}\right)+\dfrac{1}{64}-\dfrac{2}{9}-\dfrac{1}{36}+\dfrac{1}{15}$

B=$\dfrac{1}{3}-\dfrac{3}{5}+\dfrac{5}{7}-\dfrac{7}{9}+\dfrac{9}{11}-\dfrac{11}{3}+\dfrac{13}{15}+\dfrac{11}{15}-\dfrac{9}{11}+\dfrac{7}{9}+\dfrac{7}{9}-\dfrac{5}{7}+\dfrac{3}{3}-\dfrac{1}{3}$

giup minh nhe minh dang can gap

1

NL

Nguyễn Lê Phước Thịnh

27 tháng 5 2022

$A=\left(\dfrac{1}{3}+\dfrac{3}{5}+\dfrac{1}{15}\right)-\left(\dfrac{3}{4}+\dfrac{2}{9}+\dfrac{1}{36}\right)+\dfrac{1}{64}$

$=\dfrac{5+9+1}{15}-\dfrac{27+8+1}{36}+\dfrac{1}{64}$

=1/64

HT

hoang thuy an

19 tháng 9 2017

tinh nhanh

A=\dfrac{1}{3}-\dfrac{3}{4}-\left(\dfrac{-3}{5}\right)+\dfrac{1}{64}-\dfrac{2}{9}-\dfrac{1}{36}+\dfrac{1}{15}

B=\dfrac{1}{3}-\dfrac{3}{5}+\dfrac{5}{7}-\dfrac{7}{9}+\dfrac{9}{11}-\dfrac{11}{3}+\dfrac{13}{15}+\dfrac{11}{15}-\dfrac{9}{11}+\dfrac{7}{9}+\dfrac{7}{9}-\dfrac{5}{7}+\dfrac{3}{3}-\dfrac{1}{3}

giup minh nhe minh dang can gap

Thực hiện phép tính hợp lý (nếu có thể) : a) ($31\dfrac{6}{13}$ + $5\dfrac{9}{41}$ ) - $36\dfrac{6}{13}$ b) $\dfrac{5}{3}$ +( $\dfrac{-2}{7}$ ) - (-1,2) c) 0,25 + $\dfrac{3}{5}$ -...

0

LP

Lê Phương Linh

10 tháng 9 2023

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)...

2

GN

GV Nguyễn Trần Thành Đạt

Giáo viên

10 tháng 9 2023

$a,\left(31\dfrac{6}{13}+5\dfrac{9}{41}\right)-36\dfrac{6}{13}\\ =\left(31-36\right)+\left(\dfrac{6}{13}-\dfrac{6}{13}\right)+5\dfrac{9}{41}\\ =-5+0+5\dfrac{9}{41}\\ =\left(-5+5\right)+\dfrac{9}{41}=\dfrac{9}{41}$

$b,\dfrac{5}{3}+\left(-\dfrac{2}{7}\right)-\left(-1,2\right)\\ =\dfrac{5}{3}-\dfrac{2}{7}+\dfrac{6}{5}\\ =\dfrac{5.35-2.15+6.21}{105}=\dfrac{271}{105}\\ c,0,25+\dfrac{3}{5}-\left(\dfrac{1}{8}-\dfrac{2}{5}+1\dfrac{1}{4}\right)=\dfrac{1}{4}+\dfrac{3}{5}-\dfrac{1}{8}+\dfrac{2}{5}-1\dfrac{1}{4}\\ =\left(-1\dfrac{1}{4}+\dfrac{1}{4}\right)+\left(\dfrac{3}{5}+\dfrac{2}{5}\right)-\dfrac{1}{8}=-1+1-\dfrac{1}{8}=-\dfrac{1}{8}$

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KV

Kiều Vũ Linh

10 tháng 9 2023

a) (31 6/13 + 5 9/41) - 36 6/13

= 409/13 + 214/41 - 474/13

= (409/13 - 474/13) + 214/41

= -5 + 214/41

= 9/41

b) 5/3 + (-2/7) - (-1,2)

= 5/3 - 2/7 + 6/5

= 29/21 + 6/5

= 271/105

c) 0,25 + 3/5 - (1/8 - 2/5 + 1 1/4)

= 1/4 + 3/5 - 1/8 + 2/5 - 5/4

= (1/4 - 5/4) + (3/5 + 2/5) - 1/8

= -1 + 1 - 1/8

= -1/8

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TD

Thầy Đức Anh

Giáo viên VIP

27 tháng 4 2022

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) $\mathrm{D}=\dfrac{4}{9}:\left(\dfrac{1}{15}-\dfrac{10}{15}\right)+\dfrac{4}{9}:\left(\dfrac{2}{22}-\dfrac{5}{22}\right)$