Tính A = -1+3-5+7-...+2011
B = 2-4-6+8+10-12-14-16+...+98-100-102+104
C = 1-2+22_23+...+22016
Cho biểu thức A=\(\dfrac{1}{2^2}\)+\(\dfrac{1}{3^2}\)+\(\dfrac{1}{4^2}\)+\(\dfrac{1}{5^2}\)+\(\dfrac{1}{6^2}\)+\(\dfrac{1}{7^2}\)+\(\dfrac{1}{8^2}\)+\(\dfrac{1}{9^2}\)+\(\dfrac{1}{10^2}\)
Chứng minh rằng A<1
Cho A= 1/101 + 1/102 + 1/103 + 1/104 +......+ 1/200
Chứng minh : a, A > 7/12
b,A > 5/8
Cho A=1/2^2+1/2^4+1/2^6+1/2^8+...+1/2^100. Chứng minh A<1/3
Cho A= 1/2^2+ 1/2^4+ 1/2^6+ 1/2^8+...1/2^100. Chứng minh A< 1/3
Cho A=1/2^2+1/2^4+1/2^6+1/2^8+...+1/2^100
Chứng minh rằng A<1/3
1/3 .2x+5/3.2x+2=1/2 . 26 + 2 . 613
(1/3 - 1/6 ) . 2x + 2x+1=212+210
5/3 .8x+2-3/5 . 8x = 5/3 . 811 -3/5.83
Chứng minh
Chứng minh ( 245x5424x210) chia hết 7263
Chứng minh (54-53)3/125 = 64/125
Chứng minh rằng : 1/4^2+1/6^2+1/8^2+...+1/n^2<1/4
cho B = 1/4^2 +1/6^2+1/8^2 +...+1/2006^2 chứng minh B <334/2007