\(\frac{2}{3\cdot5}+\frac{2}{5\cdot7}+\frac{2}{7\cdot9}+...+\frac{2}{99\cdot101}\)
\(=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+...+\frac{1}{99}-\frac{1}{101}\)
\(=\frac{1}{3}-\frac{1}{101}\)
\(=\frac{98}{303}\)
Tích mk nha bn !!!! ^_^
\(\frac{2}{3x5}+\frac{2}{5x7}+\frac{2}{7x9}+\frac{2}{9x11}+\frac{2}{11x13}+\frac{2}{13x15}\)Tính
\(\frac{2^2}{1x3}\)x\(\frac{4^{^2}}{3x5}\)x\(\frac{6^2}{5x7}\)x\(\frac{8^2}{7x9}\)
Tính:
M = \(\frac{2}{3x5}\)+ \(\frac{2}{5x7}\)+ \(\frac{2}{7x9}\)+ ........ + \(\frac{2}{97x99}\)
Giúp mình với, x là nhân nhé
\(\frac{1}{3x5}+\frac{1}{5x7}+\frac{1}{7x9}+...+\frac{1}{2009x2011}\)
\(B=\frac{2}{1x3}+\frac{2}{3x5}+\frac{2}{5x7}+.....+\frac{2}{57x59}\)
\(\frac{2}{1x3}\)+ \(\frac{2}{3x5}\) + ........ + \(\frac{2}{99x101}\)
1/1x3+1/3X5+1/5X7+1/7X9+…+1/99X101
S=\(\frac{2}{1X3}\)+\(\frac{2}{3X5}\)+\(\frac{2}{5X7}\)+.....+\(\frac{2}{2015X2017}\)
tính A=[ 1+\(\frac{1}{3x5}\)] + [1+ \(\frac{1}{5x7}\)] +\(\left[1+\frac{1}{7x9}\right]\)+........+ \(\left[1+\frac{1}{37x39}\right]\)
