中3既數黎咩= =....
唔係中1就教麼....
minlinion 發表於 6-1-2011 20:01 http://www.nakuz.com/bbs/images/common/back.gif
我都係中三數學書先教:'(
回復 7# aaq1234
(a+b)(a+b)(a+b)
=(a+b)(a^2+ab+ba+b^2)
=(a+b)(a^2+2ab+b^2)
=a^3+2a^2b+ab^2+ba^2+2ab^2+b^3
=a^3+3a^2b+3ab^2+b^3
=a^3+b^3?
Are you kai?
(a+b)(a+b)(a+b)
= (a+b)(a^2+ab+ba+b^2)
= (a+b)(a^2+2ab+b^2)
= a^3+2a^2b+ab^2+ba^2+2ab^2+b^3
= a^3+3a^2b+3ab^2+b^3
= a^2(a+3b)+b^2(3a+b) / a^3+3ab(a+b)+b^3
點會=a^3+b^3?
應該係a^3-b^3=(a-b)(a^2+ab+b^2)
成理都加減不分,kai kai地!