\(\dfrac{1}{9}.\dfrac{2}{145}-\dfrac{13}{3}.\dfrac{2}{145}+\dfrac{2}{145}\)
\(=\dfrac{2}{145}.\left(\dfrac{1}{9}-\dfrac{13}{3}+1\right)\)
\(=\dfrac{2}{145}.\left(\dfrac{1}{9}-\dfrac{13}{3}+\dfrac{9}{9}\right)\)
\(=\dfrac{2}{145}.\left(-\dfrac{29}{9}\right)\)\(=-\dfrac{2}{45}\)
1. Tính
\(\dfrac{1}{2014}-\dfrac{1}{2014.2013}-\dfrac{1}{2013.2012}-....-\dfrac{1}{3.2}-\dfrac{1}{2.1}\)
B=\(\frac{1}{3}-\frac{3}{4}-\left(-0,6\right)+\frac{1}{64}-\frac{2}{9}-\frac{1}{36}+\frac{1}{15}\)
C=\(\frac{1}{3}-\frac{3}{5}+\frac{5}{7}-\frac{7}{9}+\frac{9}{11}-\frac{11}{13}+\frac{13}{15}+\frac{11}{15}+\frac{11}{13}-\frac{9}{11}+\frac{7}{9}-\frac{5}{7}+0,6-\frac{1}{3}\)
D=\(\frac{1}{99}-\frac{1}{99.98}-\frac{1}{98.97}.....-\frac{1}{3.2}-\frac{1}{2.1}\)
Bài 1 : Tính nhanh:
a) \(\left(\frac{5}{19}-\frac{1}{511}+\frac{7}{12}\right)-\left(-\frac{1}{511}-\frac{1}{2}+\frac{5}{19}\right)\)
b) \(-\left(\frac{13}{25}-\frac{4}{191}+\frac{2}{51}\right)+\left(\frac{4}{191}+\frac{2}{51}+\frac{3}{5}\right)\)
c) \(\frac{1}{199}-\frac{1}{199.198}-\frac{1}{198.197}-...-\frac{1}{3.2}-\frac{1}{2.1}\)
Tính nhanh :
\(C=\dfrac{1}{100}-\dfrac{1}{100.99}-\dfrac{1}{99.98}-\dfrac{1}{98.97}-....-\dfrac{1}{3.2}-\dfrac{1}{2.1}\)
a) 1/2 - (- 2/5) + 1/3 + 5/7 - (- 1/6) + (- 4/35) + 1/41
b) 1/ 100.99 - 1/ 99.98 - 1/ 98.97 - ..... - 1/ 3.2 - 1/ 2.1
1/2014 - 1/2014.2013 - 1/2013.2012 - ... - 1/3.2 - 1/2.1
1/2014 - 1/2014.2013 - 1/2013.2012 - ... - 1/3.2 - 1/2.1
1 - 1/2.1 - 1/3.2 - .. . -1/2006 . 2007 - 1/2007. 2008
1/99 - 1/99.98 - 1/98.97 - 1/97.96 -...-1/3.2 -1/2.1
