\(\Rightarrow\)P=(1-1/2).(1-1/3).(1-1/4).(1-1/5)....(1-1/2011).(1-1/2012)
\(\Rightarrow\)P=\(\dfrac{1}{2}.\dfrac{2}{3}.\dfrac{3}{4}.\dfrac{4}{5}......\dfrac{2010}{2011}.\dfrac{2011}{2012}\)
\(\Rightarrow\)P=\(\dfrac{1.2.3.4.......2010.2011}{2.3.4.5.......2011.2012}\)
\(\Rightarrow\)P=\(\dfrac{1}{2012}\)
P=(1-1/2).(1-1/3).(1-1/4).(1-1/5)....(1-1/2011).(1-1/2012)
Bài 1:
a. \(\left(5^{2010}+5^{2012}+5^{2014}\right):\left(5^{2011}+5^{2009}+5^{2007}\right)\)
b. \(\left(-\dfrac{7}{45}\right)-\left(-\dfrac{1}{4}\right)-\left(-\dfrac{3}{5}\right)+\dfrac{1}{12}+\dfrac{2}{3}+\dfrac{1}{39}-\left(-\dfrac{5}{9}\right)\)
(1-1/2)*(1-1/3)*(1-1/4)...(1-1/2011)
1. Tính tổng
A=2+4+6+...+2012 B=1+3+5+7=9+...+2013
1.
a) 9/4 - 3/4 x 1/5
b0 2/5 x 1/3 x3/5
2.
a)x : 3/4 = 2 and 2/4 + 1 and 1/4
b)7/5 : x = 2/3 x 1/4
1/3 x + 1/2 = -4/3
-2/3 - 4/3 x = -1/2
5/2 - 2 (x-1) = -2/3
7/-2 x - 1/3 = -1/2
8/5 - 1/2 : x = 8/3
-5/4 x - 1/2 x = -7/3
ét ô ét
Tìm x biết
\(\dfrac{1}{3}+\dfrac{1}{6}+\dfrac{1}{10}+...+\dfrac{2}{x\left(x+1\right)}=\dfrac{2011}{2013}\)
1+2+3+4+...+2012+2013
B= 1/1+3 + 1/1+3+5 + 1/1+3+5+7 +...+ 1/1+3+5+7+...+101
chứng minh: B<3/4
