Maths~

1.y的4次方-13y*+36.
=(y^2-4)(y^2-9)
=(y-2)(y+2)(y-3)(y+3)

2.a的3次方+b的3次方+3ab(a+b)
=a^3+3a^2b+3ab^2+b^3
=(a+b)^3

3.(x*+4x)*-2(x*+4x)- 15
=[(x*+4x)+3][(x*+4x)-5]
=(x+1)(x+3)(x+5)(x-1)

4.2(4x*+5x)*+9(4x*+5 x)+9
=[2(4x*+5 x)+3][(4x*+5 x)+3]
=(8x*+10x+3)(4x*+5x+3)
=(2x+1)(4x+3)(4x*+5x+3)

5.3(3s*+2s)*-2(3s*+2 s)-1
=[3(3s*+2 s)+1][(3s*+2 s)-1]
=(9s*+6s+1)(3s*+2s-1)
=[(3s+1)^2](3s-1)(s+1)

6.1-16乘(a的4次方)
=1-(4a^2)^2
=(1-4a^2)(1+4a^2)
=(1-2a)(1+2a)(1+4a^2)

1 y的4次方-13y*+36
=(y-9)(y-4)

2.a的3次方+b的3次方+3ab(a+b)
=(a+b)(a^2-ab+b^2)+3ab(a+b)
=(a+b)(a^2-ab+b^2+3ab)
=(a+b)(a-b)^2

3.(x*+4x)*-2(x*+4x)-15
=((x^2+4x)-5)((x^2+4x)+3)
=(x-1)(x+5)(x+1)(x+3)
- -OR- -
LET a be (x*+4x)
3.(x*+4x)*-2(x*+4x)-15
=a*-2a-15
=(a-5)(a+3)
=((x*+4x)-5)((x*+4x)+3)
=(x-1)(x+5)(x+1)(x+3)

4.2(4x*+5x)*+9(4x*+5x)+9
=(2(4x*+5x)+3)((4x*+5x)+3)
=(8x*+10x+3)(4x*+5x+3)
=(2x+1)(4x+3)(4x*+5x+3)
- OR -
LET a be(4x*+5x)
4.2(4x*+5x)*+9(4x*+5x)+9
=2a*+9a+9
=(2a+3)(a+3)
=(2(4x*+5x)+3)((4x*+5x)+3)
=(2x+1)(4x+3)(4x*+5x+3)

5.3(3s*+2s)*-2(3s*+2s)-1
=((3s*+2s)-1)(3(3s*+2s)+1)
=(3s-1)((s+1)(3s+1)^2
OR
LET y be (3s*+2s)
(3s*+2s)*-2(3s*+2s)-1
=3y^2-2y-1
=(3s-1)((s+1)(3s+1)^2

6.1-16a^4
=(1-4a*)(1+4a*)
=(1-2a)(1+2a)(1+4a*)

2007-12-16 16:44:28 補充：
1 y的4次方-13y* 36=(y*-9)(y*-4)=(y-3)(y 3)(y-2)(y 2)