1-1/6+1/6-1/11+...+1/5x+1-1/5x+6=2005/2006
1-1/5x+6=1-1/2006
5x+6=2006
5x=2000
x=400
\(1-\frac{1}{5x+6}=\frac{2005}{2006}\Leftrightarrow5x+6=2006\Leftrightarrow x=400\)
\(\frac{5}{1.6}+\frac{5}{6.11}+..+\frac{5}{\left(5x+1\right).\left(5x+6\right)}=\frac{2005}{2006}\)
tìm x,y thỏa mãn
a.\(\frac{5}{1.6}+\frac{5}{6.11}+...+\frac{5}{\left(5x+1\right).\left(5x+6\right)}=\frac{2010}{2011}\)
Tìm x :
\(\frac{1}{1.6}+\frac{1}{6.11}+\frac{1}{11.16}+..+\frac{1}{\left(5x+1\right)\left(5x+6\right)}=\frac{10}{41}\)
Tìm x:
a,\(\frac{x+1}{2}=\frac{8}{x+1}\) b,\(x:\left(9\frac{1}{2}-\frac{3}{2}\right)=\frac{0,4+\frac{2}{9}-\frac{2}{11}}{1,6+\frac{8}{9}-\frac{8}{11}}\)
c, x + (x + 1) + (x + 2) +...+ (x + 30)=1240 d) \(\frac{5}{1.6}+\frac{5}{6.11}+...+\frac{5}{\left(5x\right)+1\left(5x\right)+6}=\frac{2005}{2006}\)
\(B=\left(1-\frac{1}{4}\right).\left(1-\frac{1}{9}\right)...\left(1-\frac{1}{10000}\right)\)
\(D=\frac{5^2}{1.6}+\frac{5^2}{6.11}+\frac{5^2}{11.16}+...+\frac{5^2}{26.31}\)
Tính B và D
CMR: mọi n thuộc N ta có
\(\frac{1}{1.6}+\frac{1}{6.11}+\frac{1}{11.16}+...+\frac{1}{\left(5v+1\right).\left(5n+6\right)}=\frac{n+1}{5n+6}\)
Tính hợp lý
a, \(16\frac{3}{31}-\left(\frac{19}{28}+\frac{13}{31}\right)\)
b, \(\left(24\frac{5}{13}+7\frac{9}{46}\right)-31\frac{5}{13}\)
c, \(\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}+\frac{1}{110}\)
d,\(\frac{5^2}{1.6}+\frac{5^2}{6.11}+\frac{5^2}{11.16}+\frac{5^2}{16.21}+\frac{5^2}{21.26}+\frac{5^2}{26.31}\)
e, 1.2+2.4+3.5+4.6+5.7+.............+98.101
f,\(\left(\frac{1}{2^2}-1\right).\left(\frac{1}{3}-1\right).\left(\frac{1}{4}-1\right).............\left(\frac{1}{100^2}-1\right)\)
nói cách làm nhé ,làm dc 1 câu cũng được ^-^
Tìm x biết :
a) x + \(\frac{4}{5.9}\)+\(\frac{4}{9.13}\)+\(\frac{4}{13.17}\)+ . . . + \(\frac{4}{41.45}\)= \(-\frac{37}{45}\)
b) \(\frac{5}{1.6}\)+\(\frac{5}{6.11}\)+ . . . + \(\frac{5}{\left(5x+1\right).\left(5x+6\right)}\)=\(\frac{2015}{2016}\)
c) \(\frac{2}{1.3}\)+\(\frac{2}{3.5}\)+\(\frac{2}{5.7}\)+. . . + \(\frac{2}{x\left(x+2\right)}\)= \(\frac{2017}{2018}\)
Tính:
\(D=\frac{1}{1.6}+\frac{1}{6.11}+\frac{1}{11.16}+...+\frac{1}{\left(5n+1\right).\left(5n+6\right)}\)
Tính đầy đủ hộ mik vs. Mik đag cần gấp
