a)$\dfrac{-3}{7} \dfrac{15}{26}-\left(\dfrac{2}{13}-\dfrac{3}{7}\right)$b)$2.\dfrac{3}{7} \left(\dfrac{2}{9}-1\dfrac{3}{7}\right)-\dfrac{5}{3}:\dfrac{1}{9}$c)\(\dfrac{-11}{23}.\dfrac{6}{7} \dfrac{...

Tính nhanh a) $\dfrac{-3}{7}+\dfrac{15}{26}-\left(\dfrac{2}{13}-\dfrac{3}{7}\right)$ b) $2.\dfrac{3}{7}+\left(\dfrac{2}{9}-1\dfrac{3}{7}\right)-\dfrac{5}{3}:\dfrac{1}{9}$ c) $\dfrac{-11}{23}.\dfrac{6}{7}+\dfrac{8}{7}.\dfrac{-11}{23}-\dfrac{1}{23}$ d)...

2

NL

Nguyễn Lê Phước Thịnh

23 tháng 7 2021

a) Ta có: $\dfrac{-3}{7}+\dfrac{15}{26}-\left(\dfrac{2}{13}-\dfrac{3}{7}\right)$

$=\dfrac{-3}{7}+\dfrac{15}{26}-\dfrac{2}{13}+\dfrac{3}{7}$

$=\dfrac{15}{26}-\dfrac{4}{26}$

$=\dfrac{11}{26}$

b) Ta có: $2\cdot\dfrac{3}{7}+\left(\dfrac{2}{9}-1\dfrac{3}{7}\right)-\dfrac{5}{3}:\dfrac{1}{9}$

$=\dfrac{6}{7}+\dfrac{2}{9}-\dfrac{10}{7}-\dfrac{5}{3}\cdot9$

$=\dfrac{-4}{7}+\dfrac{2}{9}-15$

$=\dfrac{-36}{63}+\dfrac{14}{63}-\dfrac{945}{63}$

$=\dfrac{-967}{63}$

c) Ta có: $\dfrac{-11}{23}\cdot\dfrac{6}{7}+\dfrac{8}{7}\cdot\dfrac{-11}{23}-\dfrac{1}{23}$

$=\dfrac{-11}{23}\cdot\left(\dfrac{6}{7}+\dfrac{8}{7}\right)-\dfrac{1}{23}$

$=\dfrac{-11}{23}\cdot2-\dfrac{1}{23}$

$=-1$

Đúng(1)

NL

Nguyễn Lê Phước Thịnh

23 tháng 7 2021

d) Ta có: $\left(\dfrac{377}{-231}-\dfrac{123}{89}+\dfrac{34}{791}\right)\cdot\left(\dfrac{1}{6}-\dfrac{1}{8}-\dfrac{1}{24}\right)$

$=\left(\dfrac{-377}{231}-\dfrac{123}{89}+\dfrac{34}{791}\right)\cdot\left(\dfrac{4}{24}-\dfrac{3}{24}-\dfrac{1}{24}\right)$

$=\left(\dfrac{-377}{231}-\dfrac{123}{89}+\dfrac{34}{791}\right)\cdot0$

=0

Đúng(1)

NN

Nkok_ Nhỏ_Dễ_Thươg

9 tháng 4 2017

2

HH

Huỳnh Huyền Linh

9 tháng 4 2017

a) $\dfrac{-3}{7}+\dfrac{15}{26}-\left(\dfrac{2}{13}-\dfrac{3}{7}\right)\\ =\dfrac{-3}{7}+\dfrac{15}{26}-\dfrac{2}{13}+\dfrac{3}{7}\\ =\left(\dfrac{-3}{7}+\dfrac{3}{7}\right)+\left(\dfrac{15}{26}-\dfrac{2}{13}\right)\\ =0+\left(\dfrac{15}{26}-\dfrac{4}{26}\right)\\ =0+\dfrac{11}{26}\\ =\dfrac{11}{26}$

NT

Nữ Thần Mặt Trăng

9 tháng 5 2017

$c)\dfrac{-11}{23}.\dfrac{6}{7}+\dfrac{8}{7}.\dfrac{-11}{23}-\dfrac{1}{23}\\=\dfrac{-1}{23}\left ( \dfrac{66}{7}+\dfrac{88}{7}+1 \right )\\ =\dfrac{-1}{23}.23=-1$

2N

22- Nguyễn Hà Linh

17 tháng 2 2022

Tính...

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)...

0

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

Tính hợp lý: a, $\dfrac{-3}{4}.5\dfrac{3}{13}-0,75.\dfrac{36}{13}$ b, $4\dfrac{5}{9}:\left(\dfrac{-5}{7}\right)+\dfrac{49}{9}:\left(\dfrac{-5}{7}\right)$ c, $\left(\dfrac{-3}{5}+\dfrac{4}{9}\right):\dfrac{7}{11}+\left(\dfrac{-2}{5}+\dfrac{5}{9}\right):\dfrac{7}{11}$ d, $\dfrac{6}{7}:\left(\dfrac{3}{26}-\dfrac{3}{13}\right)+\dfrac{6}{7}:\left(\dfrac{1}{10}-\dfrac{8}{5}\right)$ ...

TG

Thunder Gaming

20 tháng 7 2018

#Toán lớp 7

2

V

Vivian

21 tháng 7 2018

*Trả lời :

a) $-\dfrac{3}{4}.5\dfrac{3}{13}-0,75.\dfrac{36}{13}$

= $-\dfrac{3}{4}.\dfrac{68}{13}-\dfrac{3}{4}.\dfrac{36}{13}$

=$\dfrac{3}{4}.\dfrac{-68}{13}-\dfrac{3}{4}.\dfrac{36}{13}$

=$\dfrac{3}{4}.\cdot\left(\dfrac{-68}{13}-\dfrac{36}{13}\right)$

=$\dfrac{3}{4}.\left(-8\right)$

= $-6$

b)$4\dfrac{5}{9}:\left(-\dfrac{5}{7}\right)+\dfrac{49}{9}:\left(-\dfrac{5}{7}\right)$

=$\dfrac{41}{9}-\left(-\dfrac{5}{7}\right)+\dfrac{49}{9}:\left(-\dfrac{5}{7}\right)$

=$\left(\dfrac{41}{9}+\dfrac{49}{9}\right):\left(-\dfrac{5}{7}\right)$

=$\dfrac{90}{9}:\left(-\dfrac{5}{7}\right)$

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

=$-14$

c)$\left(-\dfrac{3}{5}+\dfrac{4}{9}\right):\dfrac{7}{11}+\left(-\dfrac{2}{5}+\dfrac{5}{9}\right):\dfrac{7}{11}$

=$\left(-\dfrac{3}{5}\right)+\dfrac{4}{9}:\dfrac{7}{11}+\left(-\dfrac{2}{5}\right)+\dfrac{5}{9}:\dfrac{7}{11}$(áp dụng tính chất phá ngoặc )

=$\left\{\left[-\dfrac{3}{5}+\left(-\dfrac{2}{5}\right)\right]+\left(\dfrac{4}{9}+\dfrac{5}{9}\right)\right\}:\dfrac{7}{11}$

=$\left(-\dfrac{5}{5}+\dfrac{9}{9}\right):\dfrac{7}{11}$

=$\left(-1+1\right):\dfrac{7}{11}$

$=0:\dfrac{7}{11}$

=0.

d)$\dfrac{6}{7}:\left(\dfrac{3}{26}-\dfrac{3}{13}\right)+\dfrac{6}{7}:\left(\dfrac{1}{10}-\dfrac{8}{5}\right)$

=$\dfrac{6}{7}:\left[\dfrac{3}{26}+\left(-\dfrac{6}{26}\right)\right]+\dfrac{6}{7}:\left[\dfrac{1}{10}+\left(-\dfrac{16}{10}\right)\right]$

=$\dfrac{6}{7}:\left(-\dfrac{3}{26}\right)+\dfrac{6}{7}:\left(-\dfrac{3}{2}\right)$

=$\dfrac{6}{7}:\left[\left(-\dfrac{3}{26}\right)+\left(-\dfrac{39}{26}\right)\right]$

=$\dfrac{6}{7}:\left(-\dfrac{21}{13}\right)$

=$-\dfrac{26}{49}$

CT

Chú Thỏ Xinh Xắn

22 tháng 7 2018

-$\dfrac{4}{7}$+$\dfrac{15}{4}$-($\dfrac{11}{4}$+$\dfrac{3}{7}+\dfrac{1}{2}-\dfrac{1}{3}$) $\dfrac{1}{5}\left(\dfrac{1}{2}-\dfrac{1}{3}\right):\left(\dfrac{-9}{10}\right)+\dfrac{-7}{3}$ $\dfrac{-20}{23}+\dfrac{2}{3}-\dfrac{3}{23}+\dfrac{2}{5}+\dfrac{7}{15}$ giúp mik...

HM

Hà Mai Thùy

25 tháng 2 2023

0

H

huongff2k3

20 tháng 7 2021

tính
a)$\dfrac{-10}{11}.\dfrac{8}{9}+\dfrac{7}{18}.\dfrac{10}{11}$
b)$\dfrac{3}{14}:\dfrac{1}{28}-\dfrac{13}{21}:\dfrac{1}{28}+\dfrac{29}{42}:\dfrac{1}{28}-8$
c)$-1\dfrac{5}{7}.15+\dfrac{2}{7}\left(-15\right)+\left(-105\right).\left(\dfrac{2}{3}-\dfrac{4}{5}+\dfrac{1}{7}\right)$

7

NV

Ngo VIP PRO

20 tháng 7 2021

trẻ trâu lửa chùa

hahahaha

H

huongff2k3

20 tháng 7 2021

địt mẹ mày mày bảo cái j đấy

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

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

Tính a, 4$\times\left(-\dfrac{1}{2}\right)^3-2\times\left(-\dfrac{1}{2}\right)^2+3\times\left(-\dfrac{1}{2}\right)+1$ b, $\dfrac{4^6\times9^5+6^9\times120}{-8^4\times3^{12}+6^{11}}$ c, $\dfrac{155-\dfrac{10}{7}-\dfrac{5}{11}+\dfrac{5}{23}}{403-\dfrac{26}{7}-\dfrac{13}{11}+\dfrac{12}{23}}+\dfrac{\dfrac{3}{5}+\dfrac{3}{13}-0,9}{\dfrac{7}{91}+0,2-\dfrac{3}{10}}$ d,$\dfrac{30\times4^7\times3^{29}-5\times14^5\times2^{12}}{54\times6^{14}\times9^7-12\times8^5\times7^5}$ ...

TT

Trịnh Thị Thảo Nhi

26 tháng 7 2017

2

KL

Khánh Linh

26 tháng 7 2017

a, $4\times\left(-\dfrac{1}{2}\right)^3-2\times\left(-\dfrac{1}{2}\right)^2+3\times\left(-\dfrac{1}{2}\right)+1$

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

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

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

$=-1+1$

$=0$

@Trịnh Thị Thảo Nhi

C

chugialinh

29 tháng 4 2018

a, $4\times(-12)3-2\times(-12)2+3\times(-12)+14\times(-12)3-2\times(-12)2+3\times(-12)+1$

$=(-12)[(4\times-12)-(2\times-12)+3]+1=(-12)[(4\times-12)-(2\times-12)+3]+1$

$=(-12)(-2+1+3)+1=(-12)(-2+1+3)+1$

$=(-12)2+1=(-12)2+1$

$=-1+1=-1+1$

$=0=0$