\(P=\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{2n+1}+\frac{1}{2n+3}\)
\(P=1-\frac{1}{2n+3}\)\(
\(P=\frac{1}{1}-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+...+\frac{1}{2n+1}+\frac{1}{2n+3}\)
\(P=1-\frac{1}{2n+3}\)\(
Tình B= 1.3/3.5+2.4/5.7+3.5/7.9+....+(n-1)(n+1)/(2n-1)/2n+1 plzzzz
a,tính \(\frac{1}{1.3}+\frac{1}{3.5}+\frac{1}{5.7}+......+\frac{1}{19.21}\)
b,CMR A\(=\frac{1}{1.3}+\frac{1}{3.5}+....+\frac{1}{(2n-1).(2n+1)}\le\frac{1}{2}\)
Tính S = 1.3/3.5 + 2.4/5.7 + 3.5/7.9 + ... + ( n-1)( n+1) / (2n-1)(2n+1) + ... + 1002.1004/2005.2007
Chứng minh BĐT sau
a)\(\dfrac{1}{1.3}+\dfrac{1}{3.5}+...+\dfrac{1}{\left(2n-1\right)\left(2n+1\right)}< \dfrac{1}{2}\)
b)
CM A=1/1.3+1/3.5+...+1/(2n-1)(2n+1)<1/2
Tính tổng C = 1/1.3 + 1/3.5 + 1/5.7 + ... + 1/(2n-1) ( 2n+1) ( n thuộc N)
Tốt hok giúp vs
chứng minh rằng A=1/1.3+1/3.5+1/5.7+...+1/(2n+1).(2n+3) là phân số tối giản với mọi n thuộc N
nếu bn lm dc tặng 3 tick
Tính các tổng sau:
1.100+2.99+3.98+...+98.3+99.2+100.19+99+999+....+999...9991.2+2.3+3.4+...+n(n+1)2.4+4.6+6.8+....+2n(2n+2)1.3+2.4+3.5+...+n(n+2)1.2.3+2.3.4+3.4.5+....+n(n+1).(n+2)12+22+32+...+n2CMR n^3 - 2n^2 + 7n - 7 chia het cho n^2 + 3 voi moi n thuoc Z