Bai1 : tính hợp lí A = 17\(\dfrac{2}{31}\) - ( \(\dfrac{15}{17}\) 6\(\dfrac{2}{31}\) ) B = ( 31\(\dfrac{6}{13}\) 5\(\dfrac{9}{41}\) ) - 36\(\dfrac{9}{41}\) )

NH

nguyễn hoàng nam

25 tháng 7 2018

Bai1 : tính hợp lí A = 17\(\dfrac{2}{31}\) - ( \(\dfrac{15}{17}\) + 6\(\dfrac{2}{31}\) ) B = ( 31\(\dfrac{6}{13}\) + 5\(\dfrac{9}{41}\) ) - 36\(\dfrac{9}{41}\) ) - 36\(\dfrac{6}{13}\) C = 27\(\dfrac{51}{59}\) - ( 7\(\dfrac{51}{59}\) - \(\dfrac{1}{3}\) ) bai2: Tính A = \(\dfrac{1}{2.3}\) + \(\dfrac{1}{3.4}\) + \(\dfrac{1}{4.5}\) +...+ \(\dfrac{1}{49.50}\) B = \(\dfrac{1}{37}\) + \(\dfrac{1}{7.11}\) + \(\dfrac{1}{11.15}\)+....+\(\dfrac{1}{23.27}\) ...

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#Toán lớp 7

1

NL

Nguyễn Lê Phước Thịnh

16 tháng 8 2022

Bài 1:

a: \(=17+\dfrac{2}{31}-\dfrac{15}{17}-6-\dfrac{2}{31}=11-\dfrac{15}{17}=\dfrac{172}{17}\)

b: \(=31+\dfrac{6}{13}+5+\dfrac{9}{41}-36-\dfrac{9}{41}-36-\dfrac{6}{13}\)

=36

c: \(=27+\dfrac{51}{59}-7-\dfrac{51}{59}+\dfrac{1}{3}=20+\dfrac{1}{3}=\dfrac{61}{3}\)

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LP

Lê Phương Linh

10 tháng 9 2023 - olm

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 + \(\dfrac{3}{5}\) -...

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#Toán lớp 7

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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PT

Phạm Thảo

25 tháng 7 2018

A = 17\(\dfrac{2}{31}\) - ( \(\dfrac{15}{17}\) + 6\(\dfrac{2}{31}\) ) B = ( 31\(\dfrac{6}{13}\) + 5\(\dfrac{9}{41}\) ) - 36\(\dfrac{6}{12}\) C = 27\(\dfrac{51}{59}\) - ( 7\(\dfrac{51}{59}\) - \(\dfrac{1}{3}\) ) giúp em với em cảm ơn ...

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#Toán lớp 7

5

T

Tuyen

10 tháng 8 2018

\(A=17\dfrac{2}{31}-\left(\dfrac{15}{17}+6\dfrac{2}{31}\right)=17\dfrac{2}{31}-\dfrac{15}{17}-6\dfrac{2}{31}\)

\(=11-\dfrac{15}{17}=\dfrac{172}{17}\)

\(B=\left(31\dfrac{6}{13}+5\dfrac{9}{41}\right)-36\dfrac{6}{12}=36\dfrac{363}{533}-36\dfrac{6}{12}=\dfrac{193}{1066}\)

\(C=27\dfrac{51}{59}-\left(7\dfrac{51}{59}-\dfrac{1}{3}\right)=27\dfrac{51}{59}-7\dfrac{51}{59}+\dfrac{1}{3}=20+\dfrac{1}{3}=\dfrac{61}{3}\)

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S

Sáng

10 tháng 8 2018

\(A=17\dfrac{2}{31}-\left(\dfrac{15}{17}+6\dfrac{2}{31}\right)=17\dfrac{2}{31}-\dfrac{15}{17}-6\dfrac{2}{31}\)

\(=\left(17\dfrac{2}{31}-6\dfrac{2}{31}\right)-\dfrac{15}{17}=11-\dfrac{15}{17}=\dfrac{172}{17}\)

\(B=\left(31\dfrac{6}{13}+5\dfrac{9}{41}\right)-36\dfrac{6}{12}=36\dfrac{363}{533}-36\dfrac{1}{2}=\dfrac{193}{1066}\) (Casio :>)

\(C=27\dfrac{51}{59}-\left(7\dfrac{51}{59}-\dfrac{1}{3}\right)=27\dfrac{51}{59}-7\dfrac{51}{59}+\dfrac{1}{3}\)

\(=20+\dfrac{1}{3}=\dfrac{61}{3}\)

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NA

Ngoc Anh Thai

Giáo viên

9 tháng 5 2021

Tính một cách hợp lí:

a) \(\dfrac{27}{13}-\dfrac{106}{111}+\dfrac{-5}{111};\)

b) \(\dfrac{12}{11}-\dfrac{-7}{19}+\dfrac{12}{19};\)

c) \(\dfrac{5}{17}-\dfrac{25}{31}+\dfrac{12}{17}+\dfrac{-6}{31}.\)

#Toán lớp 6

2

MN

Minh Nhân

9 tháng 5 2021

\(a.\)

\(\dfrac{27}{13}-\dfrac{106}{111}+-\dfrac{5}{111}=\dfrac{27}{13}-\dfrac{106}{111}-\dfrac{5}{111}=\dfrac{27}{13}-\left(\dfrac{106+6}{111}\right)=\dfrac{27}{13}-1=\dfrac{14}{13}\)

\(b.\)

\(\dfrac{12}{11}-\dfrac{-7}{19}+\dfrac{12}{19}=\dfrac{12}{11}+\dfrac{7}{19}+\dfrac{12}{19}=\dfrac{12}{11}+1=\dfrac{23}{11}\)

\(c.\)

\(\dfrac{5}{17}-\dfrac{25}{31}+\dfrac{12}{17}+-\dfrac{6}{31}=\left(\dfrac{5}{17}+\dfrac{12}{17}\right)-\left(\dfrac{25}{31}+\dfrac{6}{31}\right)=1-1=0\)

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T

꧁_͏ͥ͏_͏ͣ͏_͏ͫ͏ ¡亗ᵛᶰシ๖ۣۜT๖ۣۜR๖ۣۜÂ๖ۣ...

9 tháng 5 2021

a) \(\dfrac{27}{13}-\dfrac{106}{111}+\dfrac{-5}{111}=\dfrac{27}{13}+\left(\dfrac{-106}{111}+\dfrac{-5}{111}\right)=\dfrac{27}{13}+-1=\dfrac{14}{13}\)

b) \(\dfrac{12}{11}-\dfrac{-7}{19}+\dfrac{12}{19}=\dfrac{12}{11}+\left(\dfrac{7}{19}+\dfrac{12}{19}\right)=\dfrac{12}{11}+1=\dfrac{23}{11}\)

c)\(\dfrac{5}{17}-\dfrac{25}{31}+\dfrac{12}{17}+\dfrac{-6}{31}=\left(\dfrac{5}{17}+\dfrac{12}{17}\right)+\left(\dfrac{-25}{31}+\dfrac{-6}{31}\right)=1+-1=0\)

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RM

Rina Mayano

11 tháng 9 2017

1. So sánh các tích sau hợp lý nhất: P = \(\left(-\dfrac{21}{34}\right)\)\(\left(-\dfrac{13}{27}\right)\)\(\dfrac{7}{9}\) Q = \(\left(-0,5\right)\)\(\dfrac{3}{19}\)\(\left(-\dfrac{24}{41}\right)\)\(\left(\dfrac{8}{31}\right)\) M = \(\dfrac{-6}{17}.\dfrac{-5}{17}.\) ... \(.\dfrac{5}{17}.\dfrac{6}{17}\) 2. Tính hợp lý: A = \(\left(-\dfrac{3}{11}\right).\dfrac{7}{10}.\dfrac{11}{-13}.\left(-20\right)\) B = \(\dfrac{-4}{9}:\dfrac{2}{13}+\left(\dfrac{-5}{18}\right).\dfrac{2}{13}\) C =...

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#Toán lớp 7

0

DT

Dang Tran Phong

10 tháng 4 2023

C= 2-\(\dfrac{5}{3}\)+\(\dfrac{7}{6}\)-\(\dfrac{9}{10}\)+\(\dfrac{11}{15}\)-\(\dfrac{13}{21}\)+\(\dfrac{15}{28}\)-\(\dfrac{17}{36}\)+\(\dfrac{19}{45}\)

tính C

#Toán lớp 6

1

NL

Nguyễn Lê Phước Thịnh

11 tháng 4 2023

\(=2-\left(\dfrac{5}{3}-\dfrac{7}{6}+\dfrac{9}{10}-...-\dfrac{19}{45}\right)\)

\(=2-2\left(\dfrac{5}{6}-\dfrac{7}{12}+\dfrac{9}{20}-...-\dfrac{19}{90}\right)\)

\(=2-2\left(\dfrac{1}{2}+\dfrac{1}{3}-\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}+\dfrac{1}{5}-...-\dfrac{1}{9}-\dfrac{1}{10}\right)\)

\(=2-2\cdot\dfrac{4}{10}=2-\dfrac{8}{10}=2-\dfrac{4}{5}=\dfrac{6}{5}\)

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TP

Thùy Píp

19 tháng 7 2017

tính giá trị biểu thức:

a. \(\dfrac{3}{5}\)+0,415-\(\dfrac{1}{200}\)

b. ( \(31\dfrac{6}{13}\)+5\(\dfrac{9}{41}\)) - 36\(\dfrac{6}{13}\)

c. 5. 2\(\dfrac{1}{7}\)+ 5. 7\(\dfrac{6}{7}\)

#Toán lớp 6

4

PN

Phạm Ngân Hà

19 tháng 7 2017

a) \(\dfrac{3}{5}+0,145-\dfrac{1}{200}\)

\(=\dfrac{3}{5}+\dfrac{145}{1000}-\dfrac{1}{200}\)

\(=\dfrac{3}{5}+\dfrac{29}{200}-\dfrac{1}{200}\)

\(=\dfrac{120}{200}+\dfrac{29}{200}-\dfrac{1}{200}\)

\(=\dfrac{148}{200}\)

\(=\dfrac{37}{50}\)

b) \(\left(31\dfrac{6}{13}+5\dfrac{9}{41}\right)-36\dfrac{6}{13}\)

\(=31\dfrac{6}{13}+5\dfrac{9}{41}-36\dfrac{6}{13}\)

\(=\left(31\dfrac{6}{13}-36\dfrac{6}{13}\right)+5\dfrac{5}{41}\)

\(=\left(-5\right)+5\dfrac{5}{41}\)

\(=0\dfrac{5}{41}\)

\(=\dfrac{5}{41}\)

c) \(5.2\dfrac{1}{7}+5.7\dfrac{6}{7}\)

\(=5\left(2\dfrac{1}{7}+7\dfrac{6}{7}\right)\)

\(=5\left(9+\dfrac{1}{7}+\dfrac{6}{7}\right)\)

\(=5\left(9+1\right)\)

\(=5.10\)

\(=50\)

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GD

Girl_Vô Danh

19 tháng 7 2017

a) \(\dfrac{3}{5}+0,415-\dfrac{1}{200}\)

\(=\dfrac{3}{5}+\dfrac{83}{200}-\dfrac{1}{200}\\ =\dfrac{120}{200}+\dfrac{83}{200}-\dfrac{1}{200}\\ =\dfrac{120+83-1}{200}=\dfrac{202}{200}=\dfrac{101}{100}\)

b)\(\left(31\dfrac{6}{13}+5\dfrac{9}{41}\right)-36\dfrac{6}{13}\)

\(=\left(\dfrac{409}{13}+\dfrac{214}{41}\right)-\dfrac{474}{13}\)

\(=\dfrac{19551}{533}-\dfrac{474}{13}=\dfrac{9}{41}\)

c)\(5.2\dfrac{1}{7}+5.7\dfrac{6}{7}\)

\(=5.\dfrac{15}{7}+5.\dfrac{55}{7}\\ =5\left(\dfrac{15}{7}+\dfrac{55}{7}\right)\\ =5.10=50\)

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MN

Minh Ngọc 5D - Tuệ Minh1G

5 tháng 7 2023

tính hợp lí :

a, 2 x 31 x 12 + 4 x 6 x 41+ 8 x 28 x 3

b, 3,9 x \(\dfrac{13}{10}\) + \(\dfrac{0,87}{0,01}\) x 0,39