Tính thuận tiện :
\(\frac{-10}{11}\). \(\frac{8}{9}\)+ \(\frac{7}{18}\). \(\frac{10}{11}\)
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-10/11.8/9+7/18.10/11
=10/11.-8/9+7/18.10/11
=10/11.(-8/9+7/18)
=10/11.-1/2
=-5/11
\(-\frac{10}{11}\cdot\frac{8}{9}+\frac{7}{18}\cdot\frac{10}{11}\)
\(=\frac{10}{11}\cdot\frac{-8}{9}+\frac{7}{18}\cdot\frac{10}{11}\)
\(=\frac{10}{11}\cdot\left(-\frac{8}{9}+\frac{7}{18}\right)\)
\(=\frac{10}{11}\cdot\frac{-1}{2}\)
\(=-\frac{5}{11}\)
a)
\(\begin{array}{l}\frac{{ - 3}}{{10}} - 0,125 + \frac{{ - 7}}{{10}} + 1,125 \\= \left( {\frac{{ - 3}}{{10}} + \frac{{ - 7}}{{10}}} \right) + \left( {1,125 - 0,125} \right)\\ = - 1 + 1 \\= 0\end{array}\)
b)
\(\begin{array}{l}\frac{{ - 8}}{3}.\frac{2}{{11}} - \frac{8}{3}:\frac{{11}}{9} \\= \frac{8}{3}.\frac{{ - 2}}{{11}} - \frac{8}{3}.\frac{9}{{11}}\\ = \frac{8}{3}.\left( {\frac{{ - 2}}{{11}} - \frac{9}{{11}}} \right)\\ =\frac{{ - 8}}{3}.\frac{-11}{11}\\= \frac{8}{3}.\left( { - 1} \right) \\= \frac{{ - 8}}{3}\end{array}\)
Ta có :
\(P=\frac{\frac{6}{8}+\frac{6}{10}+\frac{6}{14}+\frac{6}{26}}{\frac{11}{4}+\frac{11}{5}+\frac{11}{7}+\frac{11}{13}}\)
\(\Rightarrow P=\frac{\frac{3}{4}+\frac{3}{5}+\frac{3}{7}+\frac{3}{13}}{11\left(\frac{1}{4}+\frac{1}{5}+\frac{1}{7}+\frac{1}{13}\right)}\)
\(\Rightarrow P=\frac{3\left(\frac{1}{4}+\frac{1}{5}+\frac{1}{7}+\frac{1}{13}\right)}{11\left(\frac{1}{4}+\frac{1}{5}+\frac{1}{7}+\frac{1}{13}\right)}\)
\(\Rightarrow P=\frac{3}{11}\)
Vậy \(P=\frac{3}{11}\)
\(P=\frac{\frac{3}{4}-\frac{3}{5}+\frac{3}{7}+\frac{3}{13}}{\frac{11}{4}-\frac{11}{5}+\frac{11}{7}+\frac{11}{13}}=\frac{3}{11}\)
đề bài của bn sai nên mk sửa luôn nha
\(\frac{x}{10}=\frac{y}{6}=\frac{z}{21}\)và \(5x+y-2z=28\)
lấy (7/18+11/18)+(4/23+19/23)=2
vì 7/18+11/18=18/18=1
4/23+19/23=23/23=1
nên 1+1=2
Đ/s;2
=2
Vì 7 phần mười tám cộng 11 phần 18 bằng 1 và 4 phần 23 + 19 phần 23=1 nên 1+1=2
a, \(\frac{5}{11}\times\frac{7}{25}+\frac{15}{11}\times\frac{1}{5}\)
\(=\frac{5}{11}\times\frac{7}{25}+\frac{5}{11}\times\frac{3}{5}\)
\(=\frac{5}{11}\times\left(\frac{7}{25}+\frac{3}{5}\right)\)
\(=\frac{5}{11}\times\frac{22}{25}\)
\(=\frac{2}{5}\)
b, \(\frac{3}{7}\times\frac{25}{19}-\frac{1}{7}\times\frac{18}{19}\)
\(=\frac{1}{7}\times\frac{75}{19}-\frac{1}{7}\times\frac{18}{19}\)
\(=\frac{1}{7}\times\left(\frac{75}{19}-\frac{18}{19}\right)\)
\(=\frac{1}{7}\times3\)
\(=\frac{3}{7}\)
\(=\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+\frac{1}{10}+...+\frac{1}{10}\)có 9 p/số
\(=\frac{1}{10}.9=\frac{9}{10}\)
a ) \(\left(-\frac{40}{51}.0,32.\frac{17}{20}\right):\frac{64}{75}\)
\(=\left(-\frac{40}{51}.\frac{8}{25}.\frac{17}{20}\right):\frac{64}{75}\)
\(=\left(\frac{-40.8.17}{51.25.20}\right):\frac{64}{75}\)
\(=\left(\frac{-16}{75}\right).\frac{75}{64}\)
\(=\frac{-1}{1}.\frac{1}{4}=-\frac{1}{4}\)
a) \(\frac{14}{15}+\frac{3}{11}+\frac{1}{15}+\frac{3}{11}+\frac{10}{22}\)
\(=\left(\frac{14}{15}+\frac{1}{15}\right)+\left(\frac{3}{11}+\frac{3}{11}\right)+\frac{10}{22}\)
\(=1+1+\frac{10}{22}\)
\(=2+\frac{10}{22}\)
\(=\frac{27}{11}\)
b) 9,25 + 9,25 x 8 + 9,25
= 9,25 x ( 8 + 1 + 1 )
= 9,25 x 10
= 92,5
\(\frac{-10}{11}.\frac{8}{9}+\frac{7}{18}.\frac{10}{11}\)
\(=\frac{10}{11}.\frac{-8}{9}+\frac{7}{18}.\frac{10}{11}\)
\(=\frac{10}{11}.\left(-\frac{8}{9}+\frac{7}{18}\right)\)
\(=\frac{10}{11}.-\frac{1}{2}\)
\(=-\frac{10}{22}=-\frac{5}{11}\)