一個自己想的數學題

orb

326^2 - 325^2 = ?

要有一個快速計算的reason (知道的可在10秒內計算)

psylks

都係用 Identities 架喇~

幻藍

我type錯了....=.=""""

JOHNLAM17

Originally posted by 可愛的兔兒 at 2005-5-6 09:18 PM:

99x99
=998x1000+1
=998001

我係咁計
99²
= (100-1)²
= 10000-200+1
= 9801....

幻藍

Originally posted by snoopy11hk at 2005-5-6 05:14 PM:
...有 ar....

99 *99

99x99
=98x100+1
=9801

[ Last edited by 可愛的兔兒 on 2005-5-6 at 09:41 PM ]

oscar

其實樓主條題目...我最多2秒已經計好...

[ Last edited by oscar on 2005-5-6 at 08:40 PM ]

snoopy11hk

...有 ar....

99 *99

細薯

Originally posted by eeEric at 2005-5-6 04:33 PM:


重點是reason

(很多人都沒有說為甚麼咁計...)

a^2 - b^2 = (a + b)(a - b)

太易咪ng講lor~~

orb

Originally posted by smallpotato226 at 2005/5/6 04:26 PM:
只出一題.....
俾人做左就冇野玩 la .......><

重點是reason

(很多人都沒有說為甚麼咁計...)

細薯

只出一題.....
俾人做左就冇野玩 la .......><