F2數學....因式分解

1. (x - y)^2 - 2(x - y) + 1
= (x - y)^2 - 2(x - y)(1) + 1^2
= (x - y - 1)^2

2. x(x + 6) + 9
= x^2 + 6x + 9
= (x)^2 + 2(x)(3) + 3^2
= (x + 3)^2

3. 1 - 64(a - b)^2
= 1^2 - [8(a - b)]^2
= [1 + 8(a - b)][1 - 8(a - b)]
= (8a - 8b + 1)(8b - 8a + 1)

1) (x-y)^2-2(x-y)+1=[(x-y)-1]^2
你當(x-y)係a 1係b 咁就會見到條式係a^2-2ab+b^2
2) x(x+6)+9 = x^2+6x+9=(x+3)^2
首先乘x入去啦 之後當x係a 3係b(姐係b^2=9) 咁就見到條式係a+b)^2
3) 1-64(a-b)^2 = 1-[8(a-b)]^2 = [1-8(a+b)][1+8(a+b)]
64姐係8^2 咁當8(a+b)係b 1係a 咁就會見到係a^2-b^2=(a+b)(a-b)

1.
let x-y = z

(x-y)^2-2(x-y)+1
=z^2-2z+1
=(z-1)(z-1)
=(z-1)^2
=(x-y-1)^2

2.
x(x+6)+9
=x^2+6x+9
=(x+3)(x+3)
=(x+3)^2

3.
let a-b=c
1-64(a-b)^2
=1-8^2c^2
=1-8c^2
=(1-8c)(1+8c)

2007-12-31 16:14:11 補充：
第3題=1-8^2^2=1-(8c)^2=(1-8c)(1+8c)