【正文】
( 5 a 3 b) 3 ( a 2 b)? ? ?化簡(jiǎn)下列各式: 解 : (1) 13a+b (2) 3a +5a+3b 2 注意 : 去括號(hào)時(shí),要同時(shí)去掉括號(hào)前的括號(hào)。 23 (a 2 b)??8 2 ( 5 a b)ab? ? ?(1) (2) 去括號(hào) (a b ) (c d )? ? ?(a b ) (c d )? ? ?(a b ) 5 (c d )? ? ?( a b) ( c d)? ? ? ?(a b ) 3 (c d )? ? ?( a b) ( c d)? ? ? ?=a+b+c+d =abc+d =ab+cd =a+bc+d =a+b3c3d =a+b+5c+5d 12( x )?15 (1 )5x??1 ( 9 y 3 ) 2