Tính bằng cách thuận tiện nhất :
a) \(\frac{2}{5}+\frac{1}{6}+\frac{3}{5}\)
b) \(\frac{9}{13}+\frac{4}{13}+\frac{2}{3}\)
K
Khách
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10 tháng 9 2017
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10 tháng 9 2017
a \(\frac{4}{18}+\frac{5}{13}+\frac{7}{9}+\frac{21}{13}\)
= \(\left(\frac{4}{18}+\frac{7}{9}\right)+\left(\frac{5}{13}+\frac{21}{13}\right)\)
= \(1+2\)
= \(3\)
b \(\frac{4}{3}-\frac{2}{7}-\frac{5}{7}+\frac{2}{3}\)
= \(\left(\frac{4}{3}-\frac{2}{3}\right)-\left(\frac{2}{7}+\frac{5}{7}\right)\)
= \(\frac{2}{3}-1\)
= \(-\frac{1}{3}\)
8 tháng 4 2017
\(=\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+...+\frac{1}{10}\)có 9 p/số
\(=\frac{1}{10}.9=\frac{9}{10}\)
25 tháng 2 2018
a, \(\frac{6}{7}.\frac{16}{15}.\frac{7}{6}.\frac{21}{32}=\frac{6}{7}.\frac{7}{6}.\frac{16}{15}.\frac{21}{32}\)=\(1.\frac{16}{15}.\frac{21}{32}=\frac{7}{5.2}=\frac{7}{10}\)
Phần b T2
c,\(\frac{7}{4}.\frac{11}{21}+\frac{11}{21}.\frac{5}{4}=\frac{11}{21}.\left(\frac{7}{4}+\frac{5}{4}\right)\)=\(\frac{11}{21}.3=\frac{11}{7}\)
19 tháng 7 2016
\(\frac{2}{3}.\frac{4}{5}+\frac{1}{3}.\frac{4}{5}=\frac{4}{5}\left(\frac{2}{3}+\frac{1}{3}\right)=\frac{4}{5}.\frac{3}{3}=\frac{4}{5}.1=\frac{4}{5}\)
\(\frac{1}{2}:\frac{3}{4}+\frac{1}{6}:\frac{3}{4}=\frac{3}{4}:\left(\frac{1}{2}+\frac{1}{6}\right)=\frac{3}{4}:\frac{2}{3}=\frac{9}{8}\)
\(\frac{2}{3}.\frac{4}{5}-\frac{1}{3}.\frac{4}{5}=\frac{4}{5}\left(\frac{2}{3}-\frac{1}{3}\right)=\frac{4}{5}.\frac{1}{3}=\frac{4}{15}\)
\(\frac{1}{2}:\frac{3}{4}-\frac{1}{6}:\frac{3}{4}=\frac{3}{4}:\left(\frac{1}{2}-\frac{1}{6}\right)=\frac{3}{4}:\frac{1}{3}=\frac{9}{4}\)
19 tháng 7 2016
\(\frac{2}{3}.\frac{4}{5}+\frac{1}{3}.\frac{4}{5}=\left(\frac{2}{3}+\frac{1}{3}\right).\frac{4}{5}=1.\frac{4}{5}=\frac{4}{5}\)
\(\frac{1}{2}:\frac{3}{4}+\frac{1}{6}:\frac{3}{4}=\frac{1}{2}.\frac{4}{3}+\frac{1}{6}.\frac{4}{3}=\left(\frac{1}{2}+\frac{1}{6}\right).\frac{4}{3}=\frac{2}{3}.\frac{4}{3}=\frac{8}{9}\)
c,d tương tự
23 tháng 7 2019
\(a)\frac{4^{17}.3^4.9^6}{6^{13}}=\frac{2^{34}.3^4.3^{12}}{2^{13}.3^{13}}=\frac{2^{21}.3^{16}}{3^{13}}=2^{21}.3^3\)
\(b)\frac{2^{16}+2^8}{2^{13}+2^5}=\frac{2^8\left(2^8+1\right)}{2^5\left(2^8+1\right)}=\frac{2^3\left(2^8+1\right)}{2^8+1}=2^3=8\)
S
23 tháng 7 2019
\(a,\frac{4^{17}\times3^4\times9^6}{6^{13}}\)
\(=\frac{2^{34}\times3^4\times3^{12}}{2^{13}\times3^{13}}\)
\(=\frac{2^{34}\times3^{16}}{2^{13}\times3^{13}}\)
\(=2^{21}\times3^3\)
\(b,\frac{2^{16}+2^8}{2^{13}+2^5}\)
\(=\frac{2^8\left(2^8+2^0\right)}{2^5\left(2^8+2^0\right)}\)
\(=\frac{2^8}{2^5}\)
\(=8\)
~Study well~
24 tháng 7 2017
\(\frac{2}{3}\times\frac{3}{4}\times\frac{4}{5}=\frac{2}{5}\)
\(\frac{1}{2}:\frac{3}{4}:\frac{5}{6}=\frac{1}{2}\times\frac{4}{3}\times\frac{6}{5}=\frac{1\times2\times2}{5}=\frac{4}{5}\)
10 tháng 12 2015
= 93/4 . 7/5 - 53/4 : 5/7
=93/4 . 7/5 - 53/4 . 7/5
= 7/5 .( 93/4 - 53/4 )
= 7/5 . 10 ( rút gọn chéo 7/5 . 10 = 7 .2 =14)
= 14
tích cho mình nha
a \(\frac{7}{6}\)
b \(\frac{5}{3}\)
\(a,\frac{2}{5}+\frac{1}{6}+\frac{3}{5}\)
\(=\left(\frac{2}{5}+\frac{3}{5}\right)+\frac{1}{6}\)
\(=1+\frac{1}{6}\)
\(=\frac{7}{6}\)
Hok tốt!~