f.2因式分解3

kateau1029,briansz2000 你地究竟知唔知咩叫fatorization,咩叫expansion?
factorize x^2+2x+1
你會點做?
你會唔會將佢變成(x+1)^2,再變番做x^2+2x+1,咁咪即係冇做過野?
所謂ge factorization,
就係將一條複雜ge expression,變成一D簡單ge factor.
所謂ge expansion,
就係將一D簡單ge factor,變成一條複雜ge expression.

-(5a-b)(b-5a)
=(5a-b)(5a-b)
=(5a-b)^2
When the (b-5a) changed into (5a-b), a (-) appears. But it have one in front of (5a-b), so it cancelled the (-), change into (+).

-(5a-b)(b-5a)
= [-1(5a-b)](b-5a)
= (b-5a)(b-5a)
= b^2 - 10ab +25a^2

-(5a-b)(b-5a)

= (-5a+b)(b-5a) <-- 因為出面的「負」同括號內乘埋

=(b-5a)(b-5a)

=(b-5a)2 <-- 2次方

=(5a-b)(5a-b)
=(5a-b)^2
=25a^2-10ab+b^2

2006-11-19 22:55:29 補充：
chungmingkwan24693911未計完條數呀