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Tìm x :
x - 0,27 = \(\frac{73}{100}\)
x = \(\frac{73}{100}+0,27\)
x = 1
Cậu P khó quá mik chưa nghĩ ra cách tính nhanh nhất !
Cậu tự giải nhé !
Hok tốt
\(A=\frac{15\times3^{11}+4\times27^4}{9^7}\)
\(A=\frac{15\times177147+4\times531441}{4782969}\)
\(A=\frac{2657205+2125764}{4782969}\)
\(A=\frac{47829969}{47829969}=1\)
a,A=1/5-1/8+1/8-1/11+...+1/2006-1/2009=1/5-1/2009=2004/10045
b,B=1/4x(4/6x10+4/10x14+...+4/402x406)
=1/4x(1/6-1/10+1/10-1/14+...+1/402-1/406)
=1/4x(1/6-1/406)
=1/4x100/609=25/609
c,C=2x(5/7x12+5/12x17+...+5/502x507)
=2x(1/7-1/12+1/12-1/17+...+1/502-1/507)
=2x(1/7-1/507)
=2x500/3549
=1000/3549
Xin lỗi vì ko viết được rõ ràng.Mong bạn thông cảm. Chúc bạn học tốt.
\(\frac{3}{5\times8}+\frac{3}{8\times11}+...+\frac{3}{2006\times2009}\)
\(=\frac{1}{3}\left(\frac{3}{5\times8}+\frac{3}{8\times11}+...+\frac{3}{2006\times2009}\right)\)
\(=\frac{1}{3}\left(\frac{1}{5}-\frac{1}{8}+\frac{1}{8}-\frac{1}{11}+...+\frac{1}{2006}-\frac{1}{2009}\right)\)
\(=\frac{1}{3}\left(\frac{1}{5}-\frac{1}{2009}\right)\)
\(=\frac{1}{3}\left(\frac{1}{5}-\frac{1}{2009}\right)\)
\(=\frac{1}{3}\left(\frac{2009}{10045}-\frac{5}{10045}\right)\)
\(=\frac{1}{3}.\frac{2004}{10045}=\frac{2004}{30135}\)
Sửa đề nha :
\(\frac{1}{1\cdot3}+\frac{1}{3\cdot5}+\frac{1}{5\cdot7}+...+\frac{1}{2015\cdot2017}\)
\(=\frac{1}{2}\cdot\left(\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{2015}-\frac{1}{2017}\right)\)
\(=\frac{1}{2}\cdot\left(1-\frac{1}{2017}\right)\)
\(=\frac{1}{2}\cdot\frac{2016}{2017}=\frac{1008}{2017}\)
\(\frac{1}{1.3}+\frac{1}{3.5}+...+\frac{1}{2016.2017}\)
\(=\frac{1}{2}\left[\left[\frac{1}{1}-\frac{1}{3}\right]+\left[\frac{1}{3}-\frac{1}{5}\right]+...+\left[\frac{1}{2016}-\frac{1}{2017}\right]\right]\)
= \(=\frac{1}{2}\left[1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{2016}-\frac{1}{2017}\right]\)
\(=\frac{1}{2}.\left[1-\frac{1}{2017}\right]\)
= 1/2. 2016 / 2017 = 1008/2017
AI THẤY ĐÚNG ỦNG HỘ NHA
a) \(4+x=\frac{x+1}{5}\)
\(5.\left(4+x\right)=x+1\)
\(20+5.x=x+1\)
\(5.x-x=1-20\)
4.x = -19
x = -19/4
2) \(\frac{7}{x-1}=\frac{x}{8}\)
\(x.\left(x-1\right)=7.8\) ( x; x- 1 là 2 số tự nhiên liên tiếp)
=> x = 8
a) =\(\frac{57}{100}+\frac{17}{15}.\frac{25}{68}-\frac{1141}{500}\)
= \(\frac{57}{100}+\frac{1}{3}.\frac{5}{4}-\frac{1141}{500}\)
= \(\frac{57}{100}+\frac{5}{12}-\frac{1141}{500}\)
= -\(\frac{1943}{1500}\)
"." là nhân
b) = \(\frac{28}{15}.\frac{3}{4}-\left(\frac{8}{15}+\frac{1}{4}\right).\frac{21}{47}\)
= \(\frac{7}{5}-\frac{47}{60}.\frac{21}{47}\)
= \(\frac{7}{5}-\frac{7}{20}\)
= \(\frac{28}{20}-\frac{7}{20}\)
= \(\frac{21}{20}\)
K nhé
2. \(\frac{1995.1994-1}{1993.1995+1994}=\frac{1995.\left(1993+1\right)-1}{1993.1995+1994}=\frac{1995.1993+1995-1}{1993.1995+1994}=\frac{1995.1993+1994}{1993.1995+1994}\)
1. \(\frac{4}{3.7}+\frac{5}{7.12}+\frac{1}{12.13}+\frac{7}{13.20}+\frac{3}{20.23}\)
\(=\frac{7-3}{3.7}+\frac{12-7}{7.12}+\frac{13-12}{12.13}+\frac{23-20}{20.23}\)
\(=\left[\frac{7}{3.7}-\frac{3}{3.7}\right]+\left[\frac{12}{7.12}-\frac{7}{7.12}\right]+\left[\frac{13}{12.13}-\frac{12}{12.13}\right]+\left[\frac{20}{13.20}-\frac{13}{13.20}\right]+\left[\frac{23}{20.23}-\frac{20}{20.23}\right]\) \(=\left[\frac{1}{3}-\frac{1}{7}\right]+\left[\frac{1}{7}-\frac{1}{12}\right]+\left[\frac{1}{12}-\frac{1}{13}\right]+\left[\frac{1}{13}-\frac{1}{20}\right]+\left[\frac{1}{20}-\frac{1}{23}\right]\) \(=\frac{1}{3}-\frac{1}{7}+\frac{1}{7}-\frac{1}{12}+\frac{1}{12}-\frac{1}{13}+\frac{1}{13}-\frac{1}{20}+\frac{1}{20}-\frac{1}{23}\) \(=\frac{1}{3}-\frac{1}{23}\\ =\frac{20}{69}\)