HT
5
K
Khách
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TN
2
D
4
19 tháng 10 2017
\(\frac{20}{16}+\frac{3}{15}+\frac{2}{12}+\frac{3}{4}+\frac{4}{5}+\frac{5}{6}\)
\(=\frac{5}{4}+\frac{1}{5}+\frac{1}{6}+\frac{3}{4}+\frac{4}{5}+\frac{5}{6}\)
\(=\left(\frac{5}{4}+\frac{3}{4}\right)+\left(\frac{1}{5}+\frac{4}{5}\right)+\left(\frac{1}{6}+\frac{5}{6}\right)\)
\(=2+1+1\)
\(=4\)
TM
6
NV
12 tháng 6 2018
\(\frac{5}{6}+\frac{5}{12}+\frac{5}{20}+\frac{5}{30}+...+\frac{5}{132}+\)\(\frac{5}{156}\)
\(=5\left(\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+...+\frac{1}{132}+\frac{1}{156}\right)\)
\(=5\left(\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+...+\frac{1}{11.12}+\frac{1}{12.13}\right)\)
\(=5\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+...+\frac{1}{11}-\frac{1}{12}+\frac{1}{12}-\frac{1}{13}\right)\)
\(=5\left(\frac{1}{2}-\frac{1}{6}\right)\)
\(=5.\frac{1}{3}\)
\(=\frac{5}{3}\)
( Dấu \(.\)là dấu \(\times\)nha )
12 tháng 6 2018
5/6+5/12+5/20+...+5/132+5/156
=5*(1/6+1/12+1/20+...+1/132+1/156)
=5*[1/(2*3)+1/(3*4)+...+1/(11*12)+1/(12*13)]
=5*(1/2-1/3+1/3-1/4+..+1/11-1/12+1/12-1/13)
=5*(1/2-1/13)
=5*(11/26)
=55/26
4 tháng 12 2021
\(\frac{2}{3}\)x \(\frac{5}{8}\)x \(\frac{8}{15}\)= \(\frac{2}{3}\)x \(\frac{1}{15}\)= \(\frac{2}{45}\)
\(\frac{22}{5}\)x \(12\)x \(\frac{20}{40}\)= \(\frac{22}{5}\)x \(12\)x \(\frac{1}{2}\)= \(\frac{22}{5}\)x 6 = \(\frac{122}{5}\)
\(\frac{7}{2}\)x \(\frac{26}{7}\)x \(\frac{4}{13}\)= \(\frac{91}{7}\)x \(\frac{4}{13}\)
C
4
IA
4 tháng 4 2020
a, 2/3+1/2+1/6
=4/6+3/6+1/6
=4/3
b, 5/12+5/6-3/4
=10/24+20/24-18/24
=1/2
c, 1/3*3/5*2/5
=(1*3*2)/(3*5*5)
=2/25
d, 15/16:3/8*3/4
= 15/16*8/3*3/4
= 15/8
PV
4 tháng 4 2020
a) \(\frac{2}{3}\)+\(\frac{1}{2}\)+\(\frac{1}{6}\) = \(\frac{4}{6}\)+\(\frac{3}{6}\)+\(\frac{1}{6}\) =\(\frac{8}{6}\) =\(\frac{4}{3}\)
b)\(\frac{5}{12}+\frac{5}{6}-\frac{3}{4}\)=\(\frac{5}{12}+\frac{10}{12}-\frac{9}{12}\)=\(\frac{6}{12}\)= \(\frac{1}{2}\)
c) \(\frac{1}{3}\cdot\frac{3}{5}\cdot\frac{2}{5}\) =\(\frac{6}{75}\)=\(\frac{2}{25}\)
T
4 tháng 8 2018
\(\frac{1}{5}+\frac{1}{3}+2\frac{6}{5}\)
\(=\frac{1}{5}+\frac{1}{3}+\frac{16}{5}\)
\(=\frac{3}{15}+\frac{5}{15}+\frac{48}{15}\)
\(=\frac{3+5+48}{15}=\frac{56}{15}\)
\(\frac{7}{6}×12+\frac{14}{3}:7\)
\(=14+\frac{14}{3}×\frac{1}{7}\)
\(=14+\frac{2}{3}\)
\(=\frac{44}{3}\)
\(\frac{5×10}{20×5}=\frac{10}{20}=\frac{10:10}{20:10}=\frac{1}{2}\)
\(\frac{14×9}{7×6}=\frac{7×2×9}{7×6}=\frac{7×18}{7×6}=\frac{18}{6}=18:6=3\)
LH
4 tháng 8 2018
\(\frac{1}{5}+\frac{1}{3}+2\frac{6}{5}\)
= \(\frac{1}{5}+\frac{1}{3}+\frac{16}{5}\)
= \(\left(\frac{16}{5}+\frac{1}{5}\right)+\frac{1}{3}\)
= \(\frac{17}{5}+\frac{1}{3}\)
= \(\frac{51}{15}+\frac{5}{15}\)
= \(\frac{56}{15}\)
...
\(\frac{7}{6}.12+\frac{14}{3}:7\)
= \(14+\frac{2}{3}\)
= \(\frac{44}{3}\)
...
\(\frac{5.10}{20.5}=\frac{5.10}{10.2.5}=\frac{1}{2}\)
...
\(\frac{14.9}{7.6}=\frac{2.7.9}{7.6}=\frac{2.9}{6}=\frac{18}{6}=3\)
Hok tốt
Đặt \(A=\frac{5}{6}+\frac{5}{12}+\frac{5}{20}+...+\frac{5}{132}\)
\(A=\frac{5}{2.3}+\frac{5}{3.4}+\frac{5}{4.5}+...+\frac{5}{11.12}\)
\(A=5\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{11}-\frac{1}{12}\right)\)
\(A=5\left(\frac{1}{2}-\frac{1}{12}\right)\)
\(A=5\times\frac{5}{12}\)
\(A=\frac{25}{12}\)
ai làm nhanh mình k gấp đôi ha