F.2數學題~

(a^2 +1)^2 - 4a^2 = ?
(a^2 + 1)^2 - 4a^2
= a^4 + 2a^2 + 1 - 4a^2
= a^2 - 2a^2 + 1
= (a^2 - 1)^2

(a^2 +1)^2 - 4a^2 = ?


你把(a^2 +1)^2
看成 (a+b)^2 = (a^2 + 2ab + b^2)
姐係(a^2 +1)^2 = (a^2)^2 + 2(a^2)(1) + (1)^2

咁樣你明唔明d呀??

(a^2 +1)^2 - 4a^2

= (a^2)^2 + 2(a^2)(1) + (1)^2 -4a^2

= a^4-2a^2+1

= (a^2-1)^2

2008-02-10 16:25:50 補充：
你e條數係咪本書d數黎架??如果係應該有答案...但無step一係你post埋我答案出黎啦

(a²+1)²-4a²
=a^4+1+2a²-4a²
=a^4-2a²+1
=(a²-1)²

(a^2 +1)^2 - 4a^2
=(a^2 +1)(a^2 +1)-4a^2
=a^4+a^2 +a^2 +1 -4a^2
=1+a^4-2a^2

5知岩5岩 希望能幫您!!!

2008-02-10 22:56:50 補充：
個個都好叻!!! 識用 (a b)² = a² 2ab b² 大家都得答案=(a²-1)² but (a²-1)²=a^4-2a^2 1即我原先答案 : 1 a^4-2a^2 5知岩5岩!!!!

2008-02-10 22:57:20 補充：
個個都好叻!!! 識用 (a b)² = a² 2ab b²

2008-02-10 22:58:43 補充：
個個都好叻!!! 識用 (a+b)² = a²+2ab+b² 個加5出!!

2008-02-10 23:00:44 補充：
個個都好叻!!! 識用 (a+b)² = a²+2ab+b²大家都得答案=(a²-1)²but (a²-1)²=a^4-2a^2+1即我原先答案 : 1+a^4-2a^2 5知岩5岩!!!!

2008-02-10 23:01:40 補充：
終於得la!!! 汗""

(a^2 + 1)^2 - 4a^2
= (a^4 +2a^2 + 1) - 4a^2
= a^4 - 2a^2 + 1
= (a^2 - 1)^2

=a^4+2a^2+1-4a^2
=a^4-2a^2+1
=(a^2-1)^2
=(a+1)^2*(a-1)^2