Tính bằng cách hợp lý:$a,\dfrac{2}{3} \left(\dfrac{5}{7} \dfrac{-2}{3}\right)$ $b,\left(\dfrac{-1}{4} \dfrac{5}{8}\right) \dfrac{-3}{8}$\(c,\dfrac{7}{5}.\dfrac{8}{19} \dfrac{7}{5}.\dfrac{12}{19}-\...

0

CH

Chử Hải Yến

29 tháng 5 2022

Tính hợp lý:

$A=\dfrac{7}{12}+\dfrac{5}{12}:6-\dfrac{11}{36}$ $B=\left(\dfrac{4}{5}+\dfrac{1}{2}\right):\left(\dfrac{3}{13}-\dfrac{8}{13}\right)$

$C=\left(\dfrac{2}{3}-\dfrac{1}{4}+\dfrac{5}{11}\right):\left(\dfrac{5}{12}+1-\dfrac{7}{11}\right)$

1

NL

Nguyễn Lê Phước Thịnh

29 tháng 5 2022

a: $A=\dfrac{7}{12}+\dfrac{5}{72}-\dfrac{11}{36}=\dfrac{42}{72}+\dfrac{5}{72}-\dfrac{22}{72}=\dfrac{25}{72}$

b: $B=\dfrac{8+5}{10}:\dfrac{-5}{13}=\dfrac{13}{10}\cdot\dfrac{13}{-5}=-\dfrac{169}{100}$

c: $C=\left(\dfrac{88}{132}-\dfrac{33}{132}+\dfrac{60}{132}\right):\left(\dfrac{55}{132}+\dfrac{132}{132}-\dfrac{84}{132}\right)$

$=\dfrac{88-33+60}{55+132-84}=\dfrac{115}{103}$

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SG

Sách Giáo Khoa

17 tháng 4 2017

Tính giá trị các biểu thức sau một cách hợp lí :

$A=\dfrac{7}{19}.\dfrac{8}{11}+\dfrac{7}{19}.\dfrac{3}{11}+\dfrac{12}{19}$

$B=\dfrac{5}{9}.\dfrac{7}{13}+\dfrac{5}{9}.\dfrac{9}{13}-\dfrac{5}{9}.\dfrac{3}{13}$

$C=\left(\dfrac{67}{111}+\dfrac{2}{33}-\dfrac{15}{117}\right).\left(\dfrac{1}{3}-\dfrac{1}{4}-\dfrac{1}{12}\right)$

2

BK

Bùi Khánh Thi

17 tháng 4 2017

$A= \frac{7}{19}.\left (\frac{8}{11}+\frac{3}{11} \right )+\frac{12}{19}=\frac{7}{19}.1 +\frac{12}{19}=1$

$B=\frac{5}{9}.\left (\frac{7}{13}+\frac{9}{13}-\frac{3}{13} \right )=\frac{5}{9}.\frac{7+9-3}{13}=\frac{5}{9}.\frac{13}{13}=\frac{5}{9}.$

$C=\left (\frac{67}{111}+\frac{2}{33}-\frac{15}{117} \right ).\left (\frac{1}{3}-\frac{1}{4}-\frac{1}{12} \right )$

$=\left (\frac{67}{111}+\frac{2}{33}-\frac{15}{117} \right ).\frac{4-3-1}{12}=\left (\frac{67}{111}+\frac{2}{33}-\frac{15}{117} \right ).0=0$

NT

nguyễn thị thúy

19 tháng 4 2017

Gợi ý: Sử dụng tính chất phân phối của phép nhân đối với phép cộng để nhóm thừa số chung ra ngoài.

Giải bài 76 trang 39 SGK Toán 6 Tập 2 | Giải toán lớp 6

Tính giá trị biểu thứca, $19\dfrac{5}{8}:\dfrac{7}{12}-15\dfrac{1}{4}:\dfrac{7}{12}$ b,$\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{2}{15}:\dfrac{1}{5}+\dfrac{3}{5}.\dfrac{1}{3}$c, $\left(3\dfrac{1}{3}+2,5\right):\left(3\dfrac{1}{6}-4\dfrac{1}{5}\right)-\dfrac{11}{31}$ d, $\left[6+\left(\dfrac{1}{2}\right)^3-\left|-\dfrac{1}{2}\right|\right]:\dfrac{3}{12}$ ...

KJ

❖ Khang/GD❄ 『ʈєɑɱ❖Hoàng๖ۣۜGia☆』

27 tháng 1 2022

Bài 1.( 2 điểm)Tính bằng cách hợp...

3

R

Rhider

27 tháng 1 2022

a) $=\dfrac{157}{8}.\dfrac{12}{7}-\dfrac{61}{4}.\dfrac{12}{7}=\dfrac{12}{7}\left(\dfrac{157}{8}-\dfrac{61}{4}\right)=\dfrac{12}{7}.\dfrac{35}{8}=\dfrac{15}{2}$

b) $\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{2}{15}\div\dfrac{1}{5}+\dfrac{3}{5}.\dfrac{1}{3}=\dfrac{1}{3}\left(\dfrac{2}{5}+\dfrac{3}{5}\right)-\dfrac{2}{15}.5=\dfrac{1}{3}.1-\dfrac{2}{3}=\dfrac{1}{3}-\dfrac{2}{3}=-\dfrac{1}{3}$

c) $=-\dfrac{80}{9}$

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R

Rhider

27 tháng 1 2022

d) $=-\dfrac{1}{6}$

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F

fhdfhg

21 tháng 8 2021

1

NL

Nguyễn Lê Phước Thịnh

21 tháng 8 2021

1: $\dfrac{1}{2}+\dfrac{9}{10}+\dfrac{5}{6}-\dfrac{11}{14}-\dfrac{1}{3}+\dfrac{-4}{35}$

$=\left(\dfrac{1}{2}+\dfrac{5}{6}-\dfrac{1}{3}\right)+\dfrac{9}{10}-\left(\dfrac{11}{14}+\dfrac{4}{35}\right)$

$=\dfrac{3+5-2}{6}+\dfrac{9}{10}-\dfrac{55+8}{70}$

$=1+\dfrac{9}{10}-\dfrac{9}{10}$

=1

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TN

Trần Nguyễn Phương Thảo

VIP

11 tháng 7 2023

1.Tính hợp lí

a) $0,7+\dfrac{-7}{19}-\left(-0,3\right)$

b) $\dfrac{5}{3}.\left(-2,5\right):\dfrac{5}{6}$

c) $0,6.\dfrac{-5}{17}-\dfrac{3}{5}.\dfrac{12}{17}$

d) $\dfrac{7}{4}.\dfrac{5}{2}-\dfrac{7}{4}.\dfrac{3}{2}$

Giúp tui với!

\(\text{Thực hiện phép tính một cách hợp lý nhất (nếu có...

2

VN

Võ Ngọc Phương

VIP

11 tháng 7 2023

1. Tính hợp lí

a) $0,7+\dfrac{-7}{19}-\left(-0,3\right)$

$=\dfrac{7}{10}+\dfrac{-7}{19}+\dfrac{3}{10}$

$=\left(\dfrac{7}{10}+\dfrac{3}{10}\right)+\dfrac{-7}{19}$

$=1+\dfrac{-7}{19}$

$=\dfrac{12}{19}$

b) $\dfrac{5}{3}.\left(-2,5\right):\dfrac{5}{6}$

$=\dfrac{5}{3}.\dfrac{-5}{2}.\dfrac{6}{5}$

$=\left(\dfrac{5}{3}.\dfrac{6}{5}\right).\dfrac{-5}{2}$

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

$=-5$

c) $0,6.\dfrac{-5}{17}-\dfrac{3}{5}.\dfrac{12}{17}$

$=\dfrac{3}{5}.\dfrac{-5}{17}-\dfrac{3}{5}.\dfrac{12}{17}$

$=\dfrac{3}{5}.\left(\dfrac{-5}{17}-\dfrac{12}{17}\right)$

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

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

d) $\dfrac{7}{4}.\dfrac{5}{2}-\dfrac{7}{4}.\dfrac{3}{2}$

$=\dfrac{7}{4}.\left(\dfrac{5}{2}-\dfrac{3}{2}\right)$

$=\dfrac{7}{4}.1$

$=\dfrac{7}{4}$

Chúc bạn học tốt

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NQ

Nguyễn Quang Hưng

11 tháng 7 2023

a) $0, 7 + 19 - 7 - (- 0, 3)$

$= 10 7 + 19 - 7 + 10 3$

$= (10 7 + 10 3) + 19 - 7$

$= 1 + 19 - 7$

$= 19 12$

b) $3 5 . (- 2, 5) : 6 5$

$= 3 5 . 2 - 5 . 5 6$

$= (3 5 . 5 6) . 2 - 5$

$= 2. 2 - 5$

$= - 5$

c) $0, 6. 17 - 5 - 5 3 . 17 12$

$= 5 3 . 17 - 5 - 5 3 . 17 12$

$= 5 3 . (17 - 5 - 17 12)$

$= 5 3 . - 1$

$= 5 - 3$

d) $4 7 . 2 5 - 4 7 . 2 3$

$= 4 7 . (2 5 - 2 3)$

$= 4 7 .1$

$= 4 7$

mình giúp rùi đó nhớ tick mình nha

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E

ᴵᴬᴹɴɢᴜʏễɴ●ɴɢọᴄ●ʜùɴɢッ

30 tháng 4 2021

2

T

꧁_͏ͥ͏_͏ͣ͏_͏ͫ͏ ¡亗ᵛᶰシ๖ۣۜT๖ۣۜR๖ۣۜÂ๖ۣ...

30 tháng 4 2021

Giải:

1) (-8/13:3/7+-5/13:3/7).(-4)³.|-3|/7

=[7/3.(-8/13+-5/13)].-192/7

=[7/3.(-1)].-192/7

=-7/3.-192/7

=64

2) 75%-(5/2+5/3)+(-1/2)²

=3/4-25/6+1/4

=(3/4+1/4)-25/6

=1-25/6

=-19/6

Chúc bạn học tốt!

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TD

Thao Dong Nguyen

30 tháng 4 2021

1) $\left(\dfrac{-8}{13}:\dfrac{3}{7}+\dfrac{-5}{13}:\dfrac{3}{7}\right).\dfrac{\left(-4\right).|-3|}{7}$

= $\left[\left(\dfrac{-8}{13}+\dfrac{-5}{13}\right):\dfrac{3}{7}\right].\dfrac{-64.3}{7}$

= $\left[-1:\dfrac{3}{7}\right].\dfrac{-192}{7}$

= $\dfrac{-7}{3}.\dfrac{-192}{7}$

= $64$

2) $75\%-\left(\dfrac{5}{2}+\dfrac{5}{3}\right)+\left(-\dfrac{1}{2}\right)^2$

= $\dfrac{3}{4}-\dfrac{25}{6}+\dfrac{1}{4}$

= $\left(\dfrac{3}{4}+\dfrac{1}{4}\right)-\dfrac{25}{6}$

= $1-\dfrac{25}{6}$

= $\dfrac{-19}{6}$

Chúc bạn học tốt !

1, Tính $-2\dfrac{1}{4}.\left(3\dfrac{5}{12}-1\dfrac{2}{9}\right)$ $\left(-25\%+0,75+\dfrac{7}{12}\right):\left(-2\dfrac{1}{8}\right)$ 2, Tính nhanh $\dfrac{4}{9}.19\dfrac{1}{3}-\dfrac{4}{9}.39\dfrac{1}{3}$ | $19\dfrac{5}{8}:\dfrac{7}{12}-15\dfrac{1}{4}.\dfrac{12}{7}$ $\dfrac{-5}{7}.\dfrac{5}{11}+\dfrac{-5}{7}.\dfrac{2}{11}-\dfrac{5}{7}:\dfrac{11}{14}$ | $\dfrac{4}{7}.\dfrac{89}{5}-\dfrac{4}{5}.\dfrac{82}{7}$ $\dfrac{5}{7}.\dfrac{-4}{19}+\dfrac{-15}{7}.\dfrac{5}{19}$ |...

HC

Huyền Cơ

23 tháng 4 2017

6

PT

Phạm Thanh Hằng

25 tháng 4 2017

$-2\dfrac{1}{4}.$$\left(3\dfrac{5}{12}-1\dfrac{2}{9}\right)$

=$\dfrac{-9}{4}$.$\left(\dfrac{41}{12}-\dfrac{11}{9}\right)$

=$\dfrac{-9}{4}.\dfrac{41}{12}-\dfrac{-9}{4}.\dfrac{11}{9}$

=$\dfrac{-123}{16}-\dfrac{-11}{4}$

=$\dfrac{-123}{16}-\dfrac{-44}{16}$

=$\dfrac{-79}{16}$

PT

Phạm Thanh Hằng

25 tháng 4 2017

$\left(-25\%+0,75+\dfrac{7}{12}\right)\div\left(-2\dfrac{1}{8}\right)$

=$\left(\dfrac{-1}{4}+\dfrac{3}{4}+\dfrac{7}{12}\right)\div\left(\dfrac{-17}{8}\right)$

=$\left(\dfrac{-3}{12}+\dfrac{9}{12}+\dfrac{7}{12}\right).\dfrac{-8}{17}$

=$\dfrac{13}{12}.\dfrac{-8}{17}=\dfrac{-26}{51}$

ND

Ngân Dung

27 tháng 3 2018

$a.19\dfrac{5}{8}:\dfrac{7}{12}-15\dfrac{1}{4}:\dfrac{7}{12} b.\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{2}{15}:\dfrac{1}{5}+\dfrac{3}{5}.\dfrac{1}{3}$

c.$\left(3\dfrac{1}{3}+2,5\right):\left(3\dfrac{1}{6}-\left(4\dfrac{1}{5}\right)\right)-\dfrac{11}{31}$

1.Tính giái trị biểu thức

1

NL

Nguyễn Lê Phước Thịnh

26 tháng 6 2022

a: $=\dfrac{157}{8}\cdot\dfrac{12}{7}-\dfrac{61}{4}\cdot\dfrac{12}{7}$

$=\dfrac{12}{7}\left(\dfrac{157}{8}-\dfrac{122}{8}\right)$

$=\dfrac{12}{7}\cdot\dfrac{35}{8}=5\cdot\dfrac{3}{2}=\dfrac{15}{2}$

b: $=\dfrac{2}{15}-\dfrac{2}{15}\cdot5+\dfrac{3}{15}$

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

c: $=\left(\dfrac{10}{3}+\dfrac{5}{2}\right):\left(\dfrac{19}{6}-\dfrac{21}{5}\right)-\dfrac{11}{31}$

$=\dfrac{35}{6}:\dfrac{-31}{30}-\dfrac{11}{31}$

$=\dfrac{35}{6}\cdot\dfrac{30}{-31}-\dfrac{11}{31}$

$=\dfrac{-35\cdot5-11}{31}=\dfrac{-186}{31}=-6$

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$\left(\dfrac{13}{5}+\dfrac{7}{16}\right)+\left(\dfrac{-15}{16}+\dfrac{6}{15}\right)$ ...

HN

Hang Nguyen

22 tháng 7 2021

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