=1/5(5/1*6+5/6*11+...+5/101*106)
=1/5(1-1/6+1/6-1/11+...+1/101-1/106)
=1/5(1-1/106)
=1/5*105/106
=21/106
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Bình luận (0)
=1/5(5/1*6+5/6*11+...+5/101*106)
=1/5(1-1/6+1/6-1/11+...+1/101-1/106)
=1/5(1-1/106)
=1/5*105/106
=21/106
B=1/1.6+1/6.11+1/11.16+...+1/101.106
S=1/1.6+1/6.11+1/11.16+.....+1/496.501
S = 1/1.6+1/6.11+1/11.16+...+1/496.501
\(A=\dfrac{1}{1.6}+\dfrac{1}{6.11}+\dfrac{1}{11.16}+...+\dfrac{1}{496.501}\)
Tính :
E=1/1.6+1/6.11+1/11.16+...+1/496.501
Chứng minh 1/1.6+1/6.11+1/11.16+...+1/(5n+1)(5n+6)=n+1/5n+6
C = 1/1.6+1/6.11+1/11.16+.....+1/(5n+1).(5n+6) n thuoc N
so sánh s vs 1:
s=1/1.6+1/6.11+1/11.16+...+1/2001.1006
\(\frac{1}{1.6}+\frac{1}{6.11}+\frac{1}{11.16}+.........+\frac{1}{46.51}\)