Question

1 / 3 + 1 / 15 + 1 / 35 + 1 / 63 + 1 / 99 = ???

nhớ ghi hộ mình kết quả tối giản nhé

Answer 1

\(\frac{1}{3}\) \(+\) \(\frac{1}{15}\) \(+\) \(\frac{1}{35}\) \(+\) \(\frac{1}{63}\) \(+\) \(\frac{1}{99}\)

\(=\) \(\frac{5}{11}\)

Answer 2

\(\frac{1}{3}+\frac{1}{15}+\frac{1}{35}+\frac{1}{63}+\frac{1}{99}\)

\(=\frac{5}{11}\)

Answer 3

1\(\frac{1}{3}+\frac{1}{5x3}+\frac{1}{5x7}+\frac{1}{9x7}+\frac{1}{9x11}=\frac{1+1+1+1+1}{11}=\frac{5}{11}\)

Answer 4

\(=\frac{1}{1\times3}+\frac{1}{3\times5}+\frac{1}{5\times7}+\frac{1}{7\times9}+\frac{1}{9\times11}\)

\(=\frac{1}{2}\left(1-\frac{1}{3}+\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+\frac{1}{9}-\frac{1}{11}\right)\)

\(=\frac{1}{2}\left(1-\frac{1}{11}\right)\)

\(=\frac{1}{2}\times\frac{10}{11}=\frac{5}{11}\)

Answer 5

1/3+1/15+1/35+1/63+1/99=5/11

Answer 6

31​ $+$ \frac{1}{15}151​ $+$ \frac{1}{35}351​ $+$ \frac{1}{63}631​ $+$ \frac{1}{99}991​

$=$ \frac{5}{11}115​