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2014.18+1995+2011.2013/2013.17+671.3-671.663=-10
cách giải :2014.18+1995+2011.2013 SHIFT STO A
2013.17+671.3-671.663 SHIFT STO B
ALPHA A / ALPHA B=-10
![](https://rs.olm.vn/images/avt/0.png?1311)
(\(\frac{121}{122}\). \(\frac{123}{125}\)) .(\(\frac{1995}{1996}\).\(\frac{17}{16}\)- \(\frac{21}{25}\):\(\frac{16}{17}\)).(\(\frac{42}{30}\).\(\frac{75}{23}\)-\(\frac{19}{23}\).\(\frac{210}{38}\))
= (121/122 . 123/125) . ( 1995/1996 . 17/16 - 21/25 : 16/ 17) . 0
= 0
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\(A=\frac{1}{2}.\left(\frac{2}{1.3}+\frac{2}{3.5}+...+\frac{2}{2011.2013}\right)\)
\(A=\frac{1}{2}.\left(1-\frac{1}{2013}\right)\)
\(A=\frac{1}{2}.\frac{2012}{2013}\)
\(A=\frac{1006}{2013}\)
\(A=\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+...+\frac{1}{2011.2013}\)
\(A=\frac{1}{2}.\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{2011}-\frac{1}{2013}\right)\)
\(A=\frac{1}{2}.\left(1-\frac{1}{2013}\right)\)
\(A=\frac{1}{2}.\frac{2012}{2013}\)
\(A=\frac{1006}{2013}\)
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C = \(\frac{1.3.5.......2011.2013}{1008.1009......2013.2014}\)
C = \(\frac{1.2.3.4.5......2013.2014}{\left(2.4.6....2012.2014\right).\left(1008.1009.....2014\right)}\)
C = \(\frac{1.2.3.......2013.2014}{2^{1007}.\left(1.2.3.4.5.....1007\right).1008.1009....2014}\)
C = \(\frac{1.2.3.4.5.......2014}{2^{1007}.1.2.3.4.5.......2014}\)
C = \(\frac{1}{2^{1007}}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(=\frac{1}{3}\left(\frac{1}{3}-\frac{1}{5}\right)+\frac{1}{3}\left(\frac{1}{5}-\frac{1}{7}\right)+......+\frac{1}{3}\left(\frac{1}{2011}-\frac{1}{2013}\right)\)
\(=\frac{1}{3}\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{2011}-\frac{1}{2013}\right)\)
\(=\frac{1}{3}\left(\frac{1}{3}-\frac{1}{2013}\right)\)
\(=\frac{1}{3}x\frac{670}{2013}\)
\(=\frac{670}{6039}\)
VẬY a = \(\frac{670}{6039}\)
![](https://rs.olm.vn/images/avt/0.png?1311)
Trả lời
\(\frac{31}{17}+\left(\frac{-5}{13}\right)+\left(\frac{-8}{13}\right)-\frac{4}{17}\)
\(=\left(\frac{31}{17}-\frac{4}{17}\right)+\left[\left(\frac{-5}{13}\right)+\left(\frac{-8}{13}\right)\right]\)
\(=\frac{27}{17}+\left(\frac{-13}{13}\right)\)
\(=\frac{27}{17}+\left(-1\right)\)
\(=\frac{10}{17}\)
\(\frac{31}{17}+\frac{-5}{13}+\frac{-8}{13}-\frac{4}{17}\)
\(=\left(\frac{31}{17}-\frac{4}{17}\right)+\left(\frac{-5}{13}+\frac{-8}{13}\right)\)
\(=\frac{27}{13}+\frac{-13}{13}\)
\(=\frac{27}{13}+\left(-1\right)\)
\(=\frac{10}{17}\)
2014.18+1995+2011.2013
2013.17+671.3-671.663
=2013.18+18+1995+2011.2013
3.671.17+671.3-671.3.221
=2013.18+2013+2011.2013
3.671.17+671.3-671.3.221
=2013(18+1+2011)
671.3(17+1-221)
=2013.2030
2013.(-203)
=2030/-203=-10
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