2/7+4/5-7/12+12/7+21/5-17/12
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11 tháng 3 2022
a: =-5/11-6/11+1=-11/11+1=0
b: =-13/17-13/21-4/17=-1-13/21=-34/21
b: \(=-\dfrac{5}{12}\cdot\dfrac{9}{20}\cdot\dfrac{7}{17}=\dfrac{-21}{272}\)
d: \(=\dfrac{13}{17}\left(-\dfrac{4}{5}-\dfrac{3}{4}\right)=\dfrac{13}{17}\cdot\dfrac{-31}{20}=\dfrac{-403}{340}\)
N
4
14 tháng 4 2016
2/5 + 3/4 = 23/40
7/12 - 2/7 + 1/12 = 25/84 + 1/12 = 8/21
12/17 - 5/17 - 4/17 = 3/17
OK
14 tháng 4 2016
\(\frac{2}{5}+\frac{3}{4}=\frac{8}{20}+\frac{15}{20}=\frac{23}{20}\)
\(\frac{7}{12}-\frac{2}{7}+\frac{1}{12}=\left(\frac{7}{12}+\frac{1}{12}\right)-\frac{2}{7}=\frac{2}{3}-\frac{2}{7}=\frac{14}{21}-\frac{6}{21}=\frac{8}{21}\)
\(\frac{12}{17}-\frac{5}{17}-\frac{4}{17}=\frac{12-5-4}{17}=\frac{3}{17}\)
TQ
23 tháng 7 2016
a/ -7/2+3/4-17/12=-42/12+9/12-17/12=-50/12=-25/6
b/ 3/4+[-9/5]-4/3=45/60-108/60-80/60=-142/60=-71/30
c/ -1/12-[21/3-1/3]=-1/12-20/3=-1/12-80/12=-81/12=-27/4
d/ 22/7.[-7/11]+18= -2+18=16
e/ [3/4+2/3]:17/4-3/4=[9/12+8/12]:17/4-3/4=17/12:17/14-3/4=14/12-3/4=14/12-9/12=5/12
27 tháng 7 2021
a) Ta có: \(\dfrac{-5}{7}\left(\dfrac{14}{5}-\dfrac{7}{10}\right):\left|-\dfrac{2}{3}\right|-\dfrac{3}{4}\left(\dfrac{8}{9}+\dfrac{16}{3}\right)+\dfrac{10}{3}\left(\dfrac{1}{3}+\dfrac{1}{5}\right)\)
\(=\dfrac{-5}{7}\cdot\dfrac{3}{2}\cdot\dfrac{21}{10}-\dfrac{3}{4}\cdot\dfrac{56}{3}+\dfrac{10}{3}\cdot\dfrac{8}{15}\)
\(=\dfrac{-9}{4}-14+\dfrac{16}{9}\)
\(=\dfrac{-1621}{126}\)
b) Ta có: \(\dfrac{17}{-26}\cdot\left(\dfrac{1}{6}-\dfrac{5}{3}\right):\dfrac{17}{13}-\dfrac{20}{3}\left(\dfrac{2}{5}-\dfrac{1}{4}\right)+\dfrac{2}{3}\left(\dfrac{6}{5}-\dfrac{9}{2}\right)\)
\(=\dfrac{-17}{26}\cdot\dfrac{13}{17}\cdot\dfrac{-3}{2}-\dfrac{20}{3}\cdot\dfrac{3}{20}+\dfrac{2}{3}\cdot\dfrac{-33}{10}\)
\(=\dfrac{3}{4}-1-\dfrac{11}{5}\)
\(=-\dfrac{49}{20}\)
S
12 tháng 5 2019
2/3 * 10/21 * 3/2 = (2/3 * 3/2) * 10/21 = 1 * 10/21 = 10/21
22/5 * 12 * 5/12 = 22/5 * (12 * 5/12) = 22/5 * 5 =22
7/2 * 28/81 * 2/7= (7/2 * 2/7) * 28/81 = 1 * 28/81 =28/81
5/17 * 21/4 * 47/15 * 0 = 0
~Study well~
#Seok_Jin#
XO
7 tháng 5 2019
A =\(\frac{2}{5}\times\frac{4}{7}+\frac{3}{5}\times\frac{4}{7}\) B = \(\frac{17}{13}\times\frac{12}{17}-\frac{4}{13}\times\frac{12}{17}\) C = \(\frac{9}{14}:\frac{6}{7}+\frac{5}{14}:\frac{6}{7}\) D =\(\frac{9}{12}:\frac{7}{9}\times\frac{12}{19}\)
= \(\frac{4}{7}\times\left(\frac{2}{5}+\frac{3}{5}\right)\) =\(\left(\frac{17}{13}-\frac{4}{13}\right)\times\frac{12}{17}\) = \((\frac{9}{14}+\frac{5}{14}):\frac{6}{7}\) = \(\frac{9}{12}\times\frac{9}{7}\times\frac{12}{19}\)
=\(\frac{4}{7}\times1\) = \(1\times\frac{12}{17}\) = \(1:\frac{6}{7}\) = \(\frac{9\times9\times12}{12\times7\times19}\)
=\(\frac{4}{7}\) = \(\frac{12}{17}\) =\(\frac{7}{6}\) = \(\frac{9\times9}{7\times19}=\frac{81}{133}\)
CM
24 tháng 3 2017
13 – 6 + 8 = 7 + 8 = 15
7 + 5 – 9 = 12 – 9 = 3
17 – 8 + 6 = 9 + 6 = 15
7 + 9 – 12 = 16 – 12 = 4
14 + 6 – 17 = 20 – 17 = 3
51 + 18 – 40 = 69 – 40 = 29
43 + 7 – 21 = 50 – 21 = 29
6 + 4 – 8 = 10 – 8 = 2
12 – 3 + 8 = 9 + 8 = 17
2/7+4/5-7/12+12/7+21/5-17/12
=38/35-7/12+12/7+21/5-17/12
= 211/420+12/7+21/5-17/12
=133/60+21/5-17/12
=42/12-17/12
=23/12