Question

[tien nguyen]

\(s=\frac{5^2}{1\cdot6}+\frac{5^2}{6\cdot11}+\frac{5^2}{11\cdot16}\)

tại sao

Answer 1

[DanAlex]

\(S=5\times\left(\frac{5}{1.6}+\frac{5}{6.11}+\frac{5}{11.16}\right)\)

\(=5\times\left(1-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+\frac{1}{11}-\frac{1}{16}\right)\)

\(=5\times\left(1-\frac{1}{16}\right)\)

\(=5\times\frac{15}{16}=\frac{75}{16}\)

Vậy \(S=\frac{75}{16}\)

Answer 2

[Hoàng Tử Rồng 1411]

=5*(1-1/6+1/6-1/11+1/11-1/16)

=5*(1-1/16)

=5-5/16