A = 1/1x3 + 1/3x5 + 1/5x7 +.........+ 1/2009x2011
= 1/1-1 +1/3-5 + 1/5-7 + .......+ 1/2009-2011
= 1/1 - 1/3 + 1/3 - 1/5 + 1/5 - 1/7 +........+ 1/2009 -1/2011
= 1/1 - 1/2011
= 2010/2011
2/1x3+2/3x5+2/5x7+...+2/2009x2011
TÍNH:
\(\frac{1}{1x3}\)+\(\frac{1}{3x5}\)+\(\frac{1}{5x7}\)+....+\(\frac{1}{2009x2011}\)
GIÚP MINK NHA, THANKS, AI NHANH SẼ TICK
\(\frac{1}{3x5}+\frac{1}{5x7}+\frac{1}{7x9}+...+\frac{1}{2009x2011}\)
a=1/1x3=1/3x5+1/5x7+....+1/2019x2021+1/2021x2023
1/1x3+1/3x5+1/5x7+...+1/17x19 giúp mình nha
1/1x3+1/3X5+1/5X7+1/7X9+…+1/99X101
1/1x3 + 1/3x5 + 1/5x7 + 1/7x9 + 1/9x11
A= 1/(1x3) + 1/(3x5)+ 1/(5x7) + 1/(7x9) + 1/(9x11) = ?
chứng minh rằng tổng S=1/1x3+1/3x5+1/5x7+.............+1/2015x2017<1/2
