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23 tháng 7 2017
B. 1/3 - 1/3 - 3/5 +3/5 + 5/7 - 5/7 + 9/11 - 9/11 -11/13 + 11/ 13 + 7/9 + 13/15
= 0 -0-0-0-0+7/9 +13/15
= 74/45
Z
18 tháng 8 2019
Lời giải:
Ta có:
\(A=\left(5+\frac{1}{5}-\frac{2}{9}\right)-\left(2-\frac{1}{23}-2\frac{3}{35}+\frac{5}{6}\right)-\left(8+\frac{2}{7}-\frac{1}{18}\right)\)
\(A=5+\frac{1}{5}-\frac{2}{9}-2+\frac{1}{23}+2+\frac{3}{35}-\frac{5}{6}-8-\frac{2}{7}+\frac{1}{18}\)
\(A=\left(5-2+2-8\right)+\left(\frac{1}{5}+\frac{3}{35}-\frac{2}{7}\right)-\left(\frac{2}{9}+\frac{5}{6}-\frac{1}{18}\right)+\frac{1}{23}\)
\(A=-3+\left(\frac{7+3-10}{35}\right)-\left(\frac{4+15-1}{18}\right)+\frac{1}{23}\)
\(A=-3+0-1+\frac{1}{23}\)
\(A=-\frac{91}{23}\) . Vậy: \(A=-\frac{91}{23}\)
Chúc bạn học tốt!
Tick cho mình nhé!
SM
23 tháng 8 2018
A = \(\left(\frac{1}{15}-\frac{1}{15}\right)\)\(+\left(\frac{3}{7}-\frac{3}{7}\right)\)\(+\left(\frac{5}{9}-\frac{5}{9}\right)\)\(+\left(\frac{2}{11}-\frac{2}{11}\right)\)\(+\left(\frac{7}{13}-\frac{7}{13}\right)\)\(-\frac{9}{16}\)
A = 0 + 0 + 0 + 0 + 0 - \(\frac{9}{16}\)
A = \(-\frac{9}{16}\)
23 tháng 8 2018
\(A=\frac{1}{5}-\frac{3}{7}+\frac{5}{9}-\frac{2}{11}+\frac{7}{13}-\frac{9}{16}-\frac{7}{13}+\frac{2}{11}-\frac{5}{9}+\frac{3}{7}-\frac{1}{5}\)
\(=\left(\frac{1}{5}-\frac{1}{5}\right)-\left(\frac{3}{7}-\frac{3}{7}\right)+\left(\frac{5}{9}-\frac{5}{9}\right)-\left(\frac{2}{11}-\frac{2}{11}\right)+\left(\frac{7}{13}-\frac{7}{13}\right)-\frac{9}{16}\)
\(=0-0+0-0+0-\frac{9}{16}\)
\(=-\frac{9}{16}\)
29 tháng 3 2020
d) \(\left(3-\frac{1}{4}+\frac{2}{3}\right)-\left(5-\frac{1}{3}-\frac{6}{5}\right)-\left(6-\frac{7}{4}+\frac{3}{2}\right)\)
\(=3-\frac{1}{4}+\frac{2}{3}-5+\frac{1}{3}+\frac{6}{5}-6+\frac{7}{4}-\frac{3}{2}\)
\(=-3+\frac{3}{2}+1-5+\frac{6}{5}-\frac{3}{2}\)
\(=-7+\frac{6}{5}=-\frac{29}{5}\)
N
1 tháng 8 2019
1.
a) \(\frac{11}{2}-\frac{2}{3}:\left|2x+-\frac{3}{2}\right|=3\)
\(-\frac{2}{3}:\left|2x+-\frac{3}{2}\right|=3-\frac{11}{2}\)
\(-\frac{2}{3}:\left|2x+-\frac{3}{2}\right|=-\frac{5}{2}\)
\(\left|2x+-\frac{3}{2}\right|=-\frac{2}{3}:\left(-\frac{5}{2}\right)\)
\(\left|2x+-\frac{3}{2}\right|=\frac{4}{15}\)
\(\Rightarrow\left|2x+-\frac{3}{2}\right|\in\text{{}\frac{4}{15};-\frac{4}{15}\)}
Nếu, \(2x+\left(-\frac{3}{2}\right)=\frac{4}{15}\)
\(2x=\frac{53}{30}\)
\(x=\frac{53}{60}\)
Nếu, \(2x+\left(-\frac{3}{2}\right)=-\frac{4}{15}\)
\(2x=\frac{37}{30}\)
\(x=\frac{37}{60}\)
Vậy \(x\in\text{{}\frac{53}{60};\frac{37}{60}\)}
b) \(\left|\frac{2}{7}x-\frac{1}{5}\right|-\left|-x+\frac{4}{9}\right|=0\)
\(\left|\frac{2}{7}x-\frac{1}{5}\right|=\left|-x+\frac{4}{9}\right|\)
\(\Rightarrow\left|\frac{2}{7}x-\frac{1}{5}\right|\in\text{{}-x+\frac{4}{9};-\left(x+\frac{4}{9}\right)\)}
Nếu, \(\frac{2}{7}x-\frac{1}{5}=-x+\frac{4}{9}\)
\(x=\frac{203}{405}\)
Nếu, \(\frac{2}{7}x-\frac{1}{5}=-\left(-x+\frac{4}{9}\right)\)
\(\frac{2}{7}x-\frac{1}{5}=x-\frac{4}{9}\)
\(\frac{2}{7}x-x=\frac{1}{5}-\frac{4}{9}\)
\(-\frac{5}{7}x=-\frac{11}{45}\)
\(x=\frac{77}{225}\)
Vậy \(x\in\text{{}\frac{203}{405};\frac{77}{225}\)}
T
7 tháng 7 2019
#)Giải :
a)\(2^6.5^6=\left(2.5\right)^6=10^6\)
b)\(8^2.5^2=\left(8.5\right)^2=40^2\)
c)\(4^3.5^3=\left(4.5\right)^3=20^3\)
d)\(5^2.6^2.3^2=\left(5.6.2\right)^2=60^2\)
e)\(\frac{625^5}{25^8}=\frac{\left(25^2\right)^5}{25^8}=\frac{25^{10}}{25^8}=25^2\)
g)\(\frac{3^9}{7}.\frac{7^9}{3}=\frac{\left(3.7\right)^9}{7.3}=\frac{21^9}{21}=21^8\)
\(=\frac{-3}{7}\)
^^ mik nha !!
9/7 : (-3) = -3/7
nha anh chúc anh học tốt nha