\(tinh;\frac{1}{51\cdot100}+\frac{1}{52\cdot99}+...+\frac{1}{99\cdot52}+\frac{1}{100\cdot51}\)
\(\frac{1}{50\cdot51}+\frac{1}{51\cdot52}+\frac{1}{52\cdot53}+...+\frac{1}{99\cdot100}\)tính kết quả
Tính nhanh
\(\frac{1}{2\cdot4}+\frac{1}{4\cdot6}+\frac{1}{6\cdot8}+.........+\frac{1}{99\cdot100}\)
\(\frac{3}{1\cdot2}+\frac{3}{2\cdot3}+\frac{3}{3\cdot4}+................................................+\frac{3}{99\cdot100}\)
F=\(\frac{4}{1\cdot5}\)+ \(\frac{4}{5\cdot9}\)+.............+\(\frac{4}{99\cdot100}\)+\(\frac{2}{2\cdot4}\)+\(\frac{2}{4\cdot6}\)+..............+\(\frac{2}{99\cdot100}\)
Tính \(\frac{1}{2\cdot4}\)+\(\frac{1}{4\cdot6}+...+\frac{1}{98\cdot100}\)
tính nhanh và ko quy đồng
a] C = \(\frac{5}{2\cdot1}+\frac{4}{1\cdot11}+\frac{3}{11\cdot2}+\frac{1}{2\cdot15}+\frac{13}{15\cdot4}\)
b] B = \(\frac{6}{3\cdot5}+\frac{6}{5\cdot7}+\frac{6}{7\cdot9}+.....+\frac{6}{97\cdot99}\)
\(\dfrac{5}{1\cdot2}+\dfrac{5}{2\cdot3}+\dfrac{5}{3\cdot4}+.....+\dfrac{5}{98\cdot99}+\dfrac{5}{99\cdot100}\)
\(\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+\frac{1}{5\cdot6}=\)
k mik mik k lại