\(A=-\left(\dfrac{1}{2\cdot3}+\dfrac{1}{3\cdot4}+...+\dfrac{1}{9\cdot10}\right)\)
\(=-\left(\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{9}-\dfrac{1}{10}\right)\)
=-4/10=-2/5
\(\dfrac{1^2.a^3}{a^2.1^2}\)
tính: A=1/99 - 1/99.97 - 1/97. 95 - 1/95.93 -... - 1/5.3 - 1/3.1
B1
(-1/2)-(-3/5)+(-1/9)+1/131-(-2/7)+4/35-7/18
B2
A=1/3-3/5+5/7-7/9+9/11-11/13+13/15+11/13-9/11+7/9-5/7+3/5-1/3
B=1/99-1/99.98-1/98.97-1/97.96-...-1/3.2-1/2.1
Tính :
a) A= \(\dfrac{1}{2010.2009}-\dfrac{1}{2009.2008}-...-\dfrac{1}{3.2}-\dfrac{1}{2.1}\)
b) B= 63.(-124)-124.(-37)+(\(\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{11}\)).(-66)
Giúp mình với ạ! Mình cần gấp lắm
1/99.97-1/97.95-1/95.93........1/5.3 - 1/3.1
H = 1/99 - 97-1/97.95-1/95.93-....-1/5.3-1/3.1
1/00-1/100.99-1/99.98-1/98.97-...............-1/3.2-1/2.1
\(\dfrac{1}{50}-\dfrac{1}{50.49}-\dfrac{1}{49.48}-...-\dfrac{1}{2.1} \)
\(\dfrac{-1}{99}\dfrac{1}{99.98}-\dfrac{1}{98.97}-\dfrac{1}{97.96}-...\dfrac{1}{3.2}-\dfrac{1}{2.1}\)
Ai giúp tớ với:
Tính: \(\frac{1}{99.97}-\frac{1}{97.95}-\frac{1}{95.93}-.....-\frac{1}{5.3}-\frac{1}{3.1}\)
