中二數 唔該

1.(2x-1)(4x^2+2x+1)＜－－－－x^3-y^3=(x-y)(x^2+xy+y^2)
2.(3+z)(9-3z+z^2)＜－－－－－x^3-y^3=(x+y)(x^2-xy+y^2)
1.2(3a-4b)^2 - (4b-3a)
=2(3a-4b)^2 +(3a-4b)
=(3a-4b)2(3a-4b)+1
=(3a-4b)(6a-8b+1)
2.ax+ay-az+bx+by-bz
=a(x+y-z)+b(x+y-z)
=(a+b)(x+y-z)
3. p^2 + qr - q^2 - pr
= p^2 - pr+ qr - q^2
=p(p-r)+q(r-q)
=(p-q)(q-r)
4.(x+1)^2 - (y+1)^2
=(x+1-y+1)(x+1+y+1)
=(x-y+2)(x+y+2)＜－－－－－x^2-y^2=(x+y)(x-y)
5.8m^2 - 24mn + 18n^2
=(2m-3n)(4m-6n)
6.1 - 2a^2 + a^4
=a^4-2a^2+1
=(a^2-1)＜－－－－－－(x-y)^2=(x^2-2xy+y^2)
P.S第５題用左中三程度既方法計算

2007-07-24 07:59:39 補充：
第6題答應係(a^2-1)^2

2007-07-24 08:01:23 補充：
sorry,第４題亦有題4.(x 1)^2 - (y 1)^2=(x 1-y 1)(x 1 y-1)=(x-y 2)(x y)＜－－－－－x^2-y^2=(x y)(x-y)

2007-07-31 07:44:19 補充：
多謝樓下個位提醒,第5題我唔記得抽2出黎5.8m^2 - 24mn 18n^2=(2m-3n)(4m-6n)=2(2m-2n)(2m-3n)

2007-07-31 07:46:40 補充：
8m^2 - 24mn 18n^2=(2m-3n)(4m-6n)=2(2m-3n)(2m-3n) =2(2m-3n)^2

咁多位.......你地全部第五題都有錯= =
8m^2 - 24mn + 18n^2
2(4m^2-12mn+9n^2)
2(2m-3n)^2

1. 8x^3 - 1=(2x)^3- (1)^3=(2x-1)(4x^2+2x+1)
2. 27 + z^3=(3)^3-(z)^3=(3-z)(9+3z+z^2)

1. 2(3a-4b)^2 - (4b-3a)=(3a-4b)(2(3a-4b)+1)=(3a-4b)(6a-8b+1)
2. ax+ay+az+bx+by-bz=ax+bx+ayaz+by-bz=x(a+b)+y(a+b)+z(a+b)=(a+b)(x+y+z)
3. p^2 + qr - q^2 - pr=p^2-q^2+qr-pr=(p-q)(p+q)+r(q-p)=(p-q)(p+q-r)
4. (x+1)^2 - (y+1)^2=(x+1-y-1)(x+1+y+1)=(x-y)(x+y+2)
5. 8m^2 - 24mn + 18n^2=(2m-3n)(4m-6n)
6. 1 - 2a^2 + a^4=(1-a^2)^2