[Toán 7] Tính tổng

K

khaio

Last edited by a moderator:
L

luffy_1998

Đề nên như thế này:
$\dfrac{1}{1.2}+\dfrac{1}{2.3}+...+\dfrac{1}{99.100}$
$= 1 - \dfrac{1}{2} + \dfrac{1}{2} - \dfrac{1}{3} + ... +\dfrac{1}{99} - \dfrac{1}{100}$
$= 1 - \dfrac{1}{100}$
$= \dfrac{99}{100}$
 
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