【正文】
= – (b – a )n ( a – b )1 = – (b – a )1 ( a – b )2 = (b – a )2 ( a – b )3 = – (b – a )3 ( a – b )4 = (b – a )4 …… …… 從中你能發(fā)現(xiàn)什么規(guī)律? 例 3 把 18b ( b – a )2 – 12 ( a – b )3分解因式 . 例 3 把 18b ( b – a )2 – 12 ( a – b )3分解因式 . 18b ( b – a )2 – 12 ( a – b )3 18b ( a – b )2 – 12 ( a – b )3 6( a – b )2 6( a – b )2 ( 3b – 2a + 2b ) 6( a – b )2 ( 5b – 2a ) = = = = 解: ∴ ( b – a )2 = [– ( a – b )]2 = ( a – b )2 ∵ [ 3b – 2 ( a – b ) ] 例 3 把 18b (