M2 Binomial theorem

You can refer the following answer!


Note that i=4 to 10.
圖片參考：http://i286.photobucket.com/albums/ll87/hermittion/seriessum.jpg


2012-05-20 08:13:03 補充：
typo
the answer of b) should be -114

2012-05-20 09:33:12 補充：
sorry! typo again!!
By given the answer of b) is
-1000-20+90+6 = -924

-1000-20+90+6 = -924

BY given , b) ans. is -924.
??

a) (Σ(i=1,n) 4Ai ) = 4(Σ(i=1,n) 2-5i ) (記得Σ入個variable係 i 唔係n)
= 4(Σ(i=1,n) 2 ) - 20(Σ(i=1,n) i )
= 8n -10n(n+1)

b) by (a) with n =10 , (Σ(i=1, 10) 4Ai ) = 8(10) -10(10)(11) = -1020

(Ai 其實同 An一樣，只係個variable 唔同左。仲有野唔明可以留言)

2012-05-20 01:17:36 補充：
話時話，同binomial 有關係咩 @@?

2012-05-20 10:55:50 補充：
2樓正解. part b) 我的確計錯左.... 對不起