tính nhanh P =\(\frac{6}{7}\)*\(\frac{8}{13}+\frac{6}{9}\cdot\frac{9}{7}-\frac{3}{13}\cdot\frac{6}{7}\)
cách giải
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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,\(\frac{7}{4}.\frac{11}{21}+\frac{11}{21}.\frac{5}{4}=\frac{11}{21}.\left(\frac{7}{4}+\frac{5}{4}\right)\)=\(\frac{11}{21}.3=\frac{11}{7}\)
AT
12 tháng 2 2017
a/ \(\frac{-9}{10}.\frac{5}{14}+\frac{1}{10}.\left(\frac{-9}{2}\right)+\frac{1}{7}.\left(-\frac{9}{10}\right)\)
= \(-\frac{9}{10}.\left(\frac{5}{14}+\frac{1}{7}\right)+\frac{1}{10}.\left(-\frac{9}{2}\right)\)
= \(-\frac{9}{10}.\frac{1}{2}+\frac{1}{10}.\left(-\frac{9}{2}\right)\)
= \(\frac{-9}{20}+\left(-\frac{9}{20}\right)=\frac{-18}{20}=\frac{-9}{10}\)
b/ \(\left(\frac{1}{2}+\frac{1}{3}+\frac{1}{4}+\frac{1}{6}+\frac{1}{11}\right).132\)
\(=\left(\frac{1}{2}.132\right)+\left(\frac{1}{3}.132\right)+\left(\frac{1}{4}.132\right)+\left(\frac{1}{6}.132\right)\)\(+\left(\frac{1}{11}.132\right)\)
\(=66+44+33+22+12=177\)
c/ \(-\frac{2}{3}.\left(\frac{8}{9}.\frac{8}{13}-\frac{8}{27}.\frac{8}{13}+\frac{4}{3}.\frac{22}{39}\right)\)
= \(-\frac{2}{3}.\left[\frac{8}{13}\left(\frac{8}{9}-\frac{8}{27}\right)+\frac{88}{117}\right]\)
= \(-\frac{2}{3}.\left(\frac{8}{13}.\frac{16}{27}+\frac{88}{117}\right)\)
= còn lại làm nốt nha! bận ròy
30 tháng 4 2019
\(\frac{1}{2}\cdot\frac{1}{3}+\frac{1}{3}\cdot\frac{1}{4}+\frac{1}{4}\cdot\frac{1}{5}+\frac{1}{5}\cdot\frac{1}{6}+\frac{1}{6}\cdot\frac{1}{7}+\frac{1}{7}\cdot\frac{1}{8}+\frac{1}{8}\cdot\frac{1}{9}\)
\(=\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+\frac{1}{5\cdot6}+\frac{1}{6\cdot7}+\frac{1}{7\cdot8}+\frac{1}{8\cdot9}\)
\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{8}-\frac{1}{9}\)
\(=\frac{1}{2}-\frac{1}{9}=\frac{7}{18}\)
BD
30 tháng 4 2019
\(\frac{1}{2}\cdot\frac{1}{3}+\frac{1}{3}\cdot\frac{1}{4}+...+\frac{1}{8}\cdot\frac{1}{9}\)
\(=\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+...+\frac{1}{8\cdot9}\)
\(=\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{8}-\frac{1}{9}\)
\(=\frac{1}{2}-\frac{1}{9}\)
* LÀM NỐT *
#Louis
2 tháng 8 2015
\(\frac{6^2}{5\cdot7}\cdot\frac{7^2}{6\cdot8}\cdot\frac{8^2}{7\cdot9}\cdot\frac{9^2}{8\cdot10}\)
=\(\frac{6\cdot6}{5\cdot7}\cdot\frac{7\cdot7}{6\cdot8}\cdot\frac{8\cdot8}{7\cdot9}\cdot\frac{9\cdot9}{8\cdot10}\)
=\(\frac{6\cdot7\cdot8\cdot9}{5\cdot6\cdot7\cdot8}\cdot\frac{6\cdot7\cdot8\cdot9}{7\cdot8\cdot9\cdot10}\)
=\(\frac{9}{5}\cdot\frac{3}{5}\)=\(\frac{27}{25}\)
**** MIK
2 tháng 8 2015
\(=\frac{6.6}{5.7}.\frac{7.7}{6.8}.\frac{8.8}{7.9}.\frac{9.9}{8.10}\)
\(=\frac{6.6.7.7.8.8.9.9}{5.6.7.8.9.10.8.7}\)
\(=\frac{27}{25}\)
TD
10 tháng 3 2018
\(P=\frac{6}{7}.\frac{8}{13}+\frac{6}{9}.\frac{9}{7}-\frac{3}{13}.\frac{6}{7}\)
\(P=\frac{6}{7}.\frac{8}{13}+\frac{6}{7}-\frac{3}{13}.\frac{6}{7}\)
\(P=\frac{6}{7}.\left(\frac{8}{13}+1-\frac{3}{13}\right)\)
\(P=\frac{6}{7}.\frac{18}{13}\)
\(P=\frac{108}{91}\)
HN
10 tháng 3 2018
\(\frac{6}{7}.\frac{8}{13}+\frac{6}{9}.\frac{9}{7}-\frac{3}{13}.\frac{6}{7}\)
= \(\frac{6}{7}.\left(\frac{8}{13}-\frac{3}{13}\right)+\frac{6}{9}.\frac{9}{7}\)
= \(\frac{6}{7}.\frac{5}{13}+\frac{54}{63}\)
= \(\frac{30}{91}+\frac{54}{63}\)
= \(\frac{30}{91}+\frac{6}{7}\)
= \(\frac{30}{91}+\frac{78}{91}\)
= \(\frac{108}{91}\)
kb với em với
108/91