B = 1/1.6 + 1/6.11 + 1/11.16 + ... + 1/496.501
B x 5 = 5/1.6 + 5/6.11 + 5/11.16 + ... + 5/496.501
B x 5 = 1 - 1/6 + 1/6 - 1/11 + 1/11 - 1/16 + ... + 1/496 - 1/501
B x 5 = 1 - 1/501
B x 5 = 500/501
B = 500/501 : 5
B = 100/501
Tính A= \(\frac{1}{1.6}+\frac{1}{6.11}+\frac{1}{11.16}+.....+\frac{1}{496.501}\)
\(\frac{1}{1.6}+\frac{1}{6.11}+\frac{1}{11.16}+.........+\frac{1}{46.51}\)
tính tong 100 so hang dau tien cua day: \(\frac{1}{1.6}+\frac{1}{6.11}+\frac{1}{11.16}+\frac{1}{16.21}+.....\)
1,B=\(\frac{3}{1.6}+\frac{3}{6.11}+\frac{3}{11.16}+..............+\frac{3}{96.101}\)
Tính:A=\(\frac{1}{1.6}+\frac{1}{6.11}+\frac{1}{11.16}+...+\frac{1}{496.561}\)
Tính :
E=1/1.6+1/6.11+1/11.16+...+1/496.501
tìm số hạng thứ 100 của dãy: \(\frac{1}{1.6}+\frac{1}{6.11}+\frac{1}{11.16}+......\)
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