Question

Tính: \(\frac{1}{18}+\frac{1}{36}+.....+\frac{1}{29700}\)

Answer 1

lấy p/s cuối trừ đi p/s đầu

Answer 2

1/18 + 1/36 + ... + 1/29700

= 1/3.6 + 1/3.12 + ... 1/3.9900

= 1/3 . 1/6 + 1/3 . 1/12 + ... + 1/3 . 1/9900

= 1/3 .(1/2.3 +1/3.4 + ... + 1/99.100)

= 1/3 .(1/2 - 1/3 +1/3 -1/4 + ... + 1/99 - 1/100)

= 1/3 .(1/2 - 1/100)

= 1/3 . 49/100

= ... (cái này bạn tự tính nhé!)

Answer 3

1/18 + 1/36 + ... + 1/29700

= 1/3.6 + 1/3.12 + ... 1/3.9900

= 1/3 . 1/6 + 1/3 . 1/12 + ... + 1/3 . 1/9900

= 1/3 .(1/2.3 +1/3.4 + ... + 1/99.100)

= 1/3 .(1/2 - 1/3 +1/3 -1/4 + ... + 1/99 - 1/100)

= 1/3 .(1/2 - 1/100)

= 1/3 . 49/100

= 49/300