gọi biểu thức đó là A
\(A=\frac{1}{3.5}+\frac{1}{5.7}+.......+\frac{1}{2009.2011}\)
\(A=\frac{1}{2}.\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+.......+\frac{1}{2009}-\frac{1}{2011}\right)\)
\(A=\frac{1}{2}.\left(\frac{1}{3}-\frac{1}{2011}\right)\)
\(A=\frac{1}{2}.\left(\frac{2008}{6033}\right)\)
\(A=\frac{1004}{6033}\)
mink nghĩ vậy bạn ạ
tính: \(\frac{1}{1\times3}+\frac{1}{3\times5}+\frac{1}{5\times7}+....+\frac{1}{2009\times2011}\)
Tính nhanh : \(\frac{1}{1\times3\times5}+\frac{1}{3\times5\times7}+\frac{1}{5\times7\times9}+.....+\frac{1}{45\times47\times49}\) Help me . Mình cần gấp , HELP
\(a=\frac{1}{3\times5}+\frac{1}{5\times7}+\frac{1}{7\times9}+......+\frac{1}{2003\times2005}\)
\(\frac{1}{3\times5}+\frac{1}{5\times7}+\frac{1}{7\times9}+...+\frac{1}{\left(2x+1\right)\left(2x+3\right)}=\frac{15}{96}\)
Tìm x biết \(\frac{1}{3\times5}+\frac{1}{5\times7}+\frac{1}{7\times9}+...+\frac{1}{\left(2x+1\right)\left(2x+3\right)}=\frac{15}{93}\)
\(\frac{1}{2\times3}+\frac{1}{3\times4}+\frac{1}{4\times5}+\frac{1}{5\times6}+\frac{1}{6\times7}+\frac{1}{7\times8}+\frac{1}{8\times9}+\frac{1}{9\times10}\)
Giúp mình với!!!!!
Tính:
G=\(\frac{1}{1\times3\times5}+\frac{1}{5\times7\times9}+\frac{1}{9\times11\times13}+...+\frac{1}{49\times51\times53}\)
Tính
a) \(M=\frac{2}{3\times5}+\frac{2}{5\times7}+\frac{2}{7\times9}+...+\frac{2}{97\times99}\)
b) \(N=\frac{3}{5\times7}+\frac{3}{7\times9}+\frac{3}{9\times11}+...+\frac{3}{197\times199}\)
Các bạn giúp mk nha! Cần lắm! Thanks các bạn nhiều
C= \(\frac{3}{3\times5}+\frac{3}{5\times7}+\frac{3}{7\times9}+....+\frac{3}{47\times49}\)
