（6a+a²+9）（6a-a²-9）可以因式分解吗,

（6a+a²+9）（6a-a²-9）可以因式分解吗,

( 6a + a" + 9 )( 6a - a" - 9 )
= -( a" - 6a + 9 )( a" + 6a + 9 )
= -( a - 3 )"( a + 3 )"
或者
= ( 3a + a" + 9 + 3a )( 3a - a" - 9 + 3a )
= [ a( 3 + a ) + 3( 3 + a ) ][ a( 3 - a ) - 3( 3 - a ) ]
= ( 3 + a )( 3 + a )( 3 - a )( a - 3 )
= -( 3 - a )"( 3 + a )"
完全平方,看清楚了吗?

=-（a²-9）⒋

(a+3)²-(a-3)²
=[(a+3)+(a-3)][(a+3)-(a-3)]

[6a+(a^2+9)][6a-(a^2+9)]