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[Giải:]
= 31955 . 359 . (23)19 / ( 2 . 3)60 . 31955
= 359 . 257 / 260 . 360
= 359 . 257 / 257 . 23 . 359 . 3
= 1/23 . 3
= 1/24
[ Hoq chắc - Thắc mắc -> ib hỏi ]
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\(A=\frac{1}{19}+\frac{2}{19^2}+...+\frac{2014}{19^{2014}}\)
\(\Rightarrow19A=1+\frac{2}{19}+\frac{3}{19^2}+...+\frac{2014}{19^{2013}}\)
\(\Rightarrow19A-A=\left(1+\frac{2}{19}+\frac{3}{19^2}+...+\frac{2014}{19^{2013}}\right)-\left(\frac{1}{19}+\frac{2}{19^2}+...+\frac{2014}{19^{2014}}\right)\)
\(\Rightarrow18A=1+\left(\frac{1}{19}+\frac{1}{19^2}+...+\frac{1}{19^{2013}}\right)-\frac{2014}{19^{2014}}\)
\(\Rightarrow18A=1+\frac{1-\frac{1}{19^{2013}}}{18}-\frac{2014}{19^{2014}}\)
\(\Rightarrow A=\frac{1+\frac{1-\frac{1}{19^{2013}}}{18}-\frac{2014}{19^{2014}}}{18}\)
Vậy...
![](https://rs.olm.vn/images/avt/0.png?1311)
\(1\frac{13}{15}\cdot\left(0,5\right)^2\cdot3-\left(\frac{8}{15}+1\frac{19}{60}\right):1\frac{19}{60}\)
\(=\frac{28}{15}\cdot\frac{1}{4}\cdot\frac{3}{1}-\frac{37}{20}\cdot\frac{60}{79}\)
\(=\frac{7}{5}-\frac{111}{79}\)
\(=\frac{-2}{395}\)
=28/15.1/4.3-8/15-79/60.60/79
=7.4/15.1/4.3-8/15-1
=7/15.3-8/15-1
=21/15-8/15-1
=13/15-1
=-2/15
\(=\frac{3^{2014}.\left(2^3\right)^{19}}{2^{60}.3^{60}.3^{1955}}\)
\(=\frac{3^{2014}.2^{57}}{2^{60}.3^{2015}}\)
\(=\frac{1}{2^3.3}=\frac{1}{24}\)
P/S: bn vt sai đề rồi lần sau cẩn thận tí nha