因式分解.........

(4y^2+12xy+9y^2)(4y^2-12xy+9y^2)-9x^4
= y(4y+12x+9y)(4y-12x+9y)-9x^4
=y(13y+12x)(13y-12x)-9x^4
=y[13y(13y-12x)+12x(13y-12x)]-9x^4
=y(169y^2-156xy+156xy-144x^2)-9x^4
=y(169y^2 - 144x^2) -9x^4

2007-05-29 15:44:50 補充：
你條題目好似唔係咁架應該係(4x^2 12xy 9y^2)(4x^2-12xy 9y^2)-9x^4先計到架

2007-05-29 22:30:44 補充：
根本你條題目就係錯...你自己check 下啦..

2007-06-07 22:38:47 補充：
計好喇 !!(4x^2 + 12xy + y^2)(4x^2 - 12xy + 9y^2) - 9x^4=(4x^2 + 9y^2 + 12xy)(4x^2 + 9y^2 - 12xy) - 9x^4=(4x^2 + 9y^2)^2 - 144x^2y^2 - 9x^4=16x^4 + 72x^2y^2 + 81y^4 - 144x^2y^2 - 9x^4=7x^4 - 72x^2y^2 + 81y^4=(7x^2 - 9y^2)(x^2 - 9y^2)=(7x^2 - 9y^2)(x 3y)(x - 3y)

(4y^2+12xy+9y^2)(4y^2-12xy+9y^2)-9x^4


=(2y+3y)^2(2y-3y)^2-(3x^2)^2


=(5y)^2*(-y)^2-(3x^2)^2


=25y^2*y^2-(3x^2)^2


=25y^4-9x^4


=(5y+3x^2)(5y-3x^2)

(4y^2+12xy+9y^2)(4y^2-12xy+9y^2)-9x^4
=(13y^2+12xy)(13y^2-12xy) - 9x^4
=169y^4 - 144x^2y^2 - 9x^4

2007-05-30 17:25:07 補充：
我都覺得係你個問題錯....下次小心o的打問題出o黎啦.....

2007-06-05 14:06:10 補充：
(4x^2 12xy 9y^2)(4x^2 - 12xy 9y^2) - 9x^4=(4x^2 9y^2 12xy)(4x^2 9y^2 - 12xy) - 9x^4=(4x^2 9y^2)^2 - 144x^2y^2 - 9x^4=16x^4 72x^2y^2 81y^4 - 144x^2y^2 - 9x^4=7x^4 - 72x^2y^2 81y^4=(7x^2 - 9y^2)(x^2 - 9y^2)=(7x^2 - 9y^2)(x 3y)(x - 3y)

(4y^2+12xy+9y^2)(4y^2-12xy+9y^2)-9x^4
= (2y+3x)^2(2y-3x)^2-(3x^2)^2
=[(2y+3x)(2y-3x)]^2-(3x^2)^2
=(4y^2-9x^2)^2-(3x^2)^2
=(4y^2-9x^2+3x^2)(4y^2-9x^2-3x^2)
=(4y^2-6x^2)(4y^2-12x^2)
=8(2y^2-3x^2)(y^2-3x^2)

* make use of A^2-B^2 = (A+B)(A-B)

(4y^2+12xy+9y^2)(4y^2-12xy+9y^2)-9x^4
=(4y^2)^2-(12xy+9y^2)^2-9x^4
=16y^4 - 144x^2y^2 -216xy^3 - 81y^4 - 9x^4
=-9x^4 - 65y^4 - - 144x^2y^2 -216xy^3

2007-05-29 07:36:44 補充：
=-9x^4 - 65y^4 - 144x^2y^2 -216xy^3