Chứng Minh :
1/5^2+1/5^4+1/5^6+........+1/5^2014 < 1/24
So sánh :
A=(-3/5)^5 và B=(-5/243)^3
Chứng Minh :
3/1.11+3/2.6+3/3.8+....+1/2012.1342 < 15
Cho x/y=1/1.2+1/3.4+1/5.6+....+1/99.100
a-C/M x/y=1/51+1/52+1/53+.....+1/100
b-CM x chia hết cho 151
1)5^x.5^(x+1).5^(x+2)=100.....0000:2^18
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18 c/s 0