中二數學　要列式

(1) -20p(3p-2)^2-20(3p-2)p-5p
=-5p [ 4(3p-2)^2 + 4(3p-2)+1 ]
=-5p [ 2(3p-2)+1 ]^2

(2) x^2-12xy+36y^2-x+6y
=(x^2-12xy+36y^2) - (x-6y)
=(x-6y)^2 - (x-6y)
=(x-6y) (x-6y-1)

(3) x^6+2x^4y^2+y^4x^2-4
= (x^6 + 2x^4 y^2 + y^4 x^2) - 4
=x^2 ( x^4 + 2x^2 y^2 + y^4) - 4
=x^2 (x^2 + y^2)^2 - 4
= [ x (x^2 + y^2) + 2] [ x (x^2 + y^2) - 2]

(4) a^6 k^6 - 1<-- 會唔會打錯? 照計應該冇得factorise...至少我唔識計..


(5) a^3 - b^3 + 3a b^2 - 3a^2 b
= ( a^3 - b^3 ) +
= (a - b) ( a^2 + ab + b^3 ) + 3ab ( b - a )
= (a - b) ( a^2 + ab + b^3 ) - 3ab ( a - b )
= (a - b) ( a^2 + ab + b^3 - 3ab)
= (a - b) ( a^2 - 2ab + b^3)


ps. " ^ " 係次方
有唔明再問la, 希望幫到你=]

2007-12-25 23:41:04 補充：
(5) a^3 - b^3 3a b^2 - 3a^2 b= ( a^3 - b^3 ) 3a b^2 - 3a^2 b= (a - b) ( a^2 ab b^3 ) 3ab ( b - a )= (a - b) ( a^2 ab b^3 ) - 3ab ( a - b )= (a - b) ( a^2 ab b^3 - 3ab)= (a - b) ( a^2 - 2ab b^3)打漏咗少少嘢...唔好意思

2007-12-25 23:46:38 補充：
(5) a^3 - b^3 3a b^2 - 3a^2 b= ( a^3 - b^3 ) 3a b^2 - 3a^2 b= (a - b) ( a^2 ab b^3 ) 3ab ( b - a )= (a - b) ( a^2 ab b^3 ) - 3ab ( a - b )= (a - b) ( a^2 ab b^3 - 3ab)= (a - b) ( a^2 - 2ab b^3)呢次應該OK的了~

1.
-20p(3p-2)² -20(3p-2)p -5p
= -5p [4(3p-2)² + 4(3p-2) + 1]
= -5p [2(3p-2)+1]²
= -5p (6p-4+1)²
= -5p (6p-3)²
= -5p [3(2p-1)]²
= -5p (3²) (2p-1)]²
= -5p (9) (2p-1)²
= -45p(2p-1)²

2.
x²-12xy+36y²-x+6y
=(x-6y)² -(x-6y)
=(x-6y)(x-6y-1)

3.
x^6+2x^4y^2+y^4x^2 - 4
=x^2(x^4+2x^2y^2+y^4) - 4
= x^2(x^2+y^2)² - 4
= x²(x²+y²)² - 4
= [x(x²+y²)]² - (2)²
= [x(x²+y²)+2] [x(x²+y²)-2]
= (x³+xy²+2) (x³+xy²-2)

4.
a^6k^6 - 1
= (a³k³)² - 1
= (a³k³ - 1) (a³k³ + 1)
= [(ak)³ - 1³] [(ak)³ + 1³]
= (ak - 1)(a²k² + ak + 1) (ak + 1)(a²k² - ak + 1)

5.
a³ - b³ + 3ab² - 3a²b
= (a - b) (a² + ab + b²) - 3ab (a - b)
= (a - b) (a² + ab + b² - 3ab)
= (a - b) (a² - 2ab + b²)
= (a - b) (a - b)²
= (a - b)³

希望幫到你!
有錯請指正!