✔ 最佳答案
其實我唔太明因式分解係將
x^2 - y^2 轉做 (x+y)(x-y)
定係
(x+y)(x-y)轉做x^2 - y^2
我見到你呢7題好似兩種形式都有...
1.
a^2 - 2ab + b^2 - a + b
= (a-b)^2 - (a-b)
= (a-b)(a-b) - (a-b)
= (a-b)(a-b-1)
註 a^2 姐係a既2次方 普通會考用計數機都會有呢個符號
以後係電腦入x既y次方可以咁表達
2.
a(3b-c)+c-3b
=3ab-ac+c-3b
=3ab-3b - ac+c
=3b(a-1) - c(a-1)------------------- 抽(a-1)呢個common factor出黎
=(3b-c)(a-1)
3.
x^2 - 2x+1- 4y^2
=(x-1)^2 - 4y^2
=(x-1)^2 - (2y)^2 --------- 常用分解用既公式x^2-y^2 = (x+y)(x-y)
=(x-1+2y)(x-1-2y) 你呢7題都用左好多咁既
4.
(x^2+4^x+4)-(y-1)^2------ 都係常用分解用公式(a+b)^2 =a^2+2ab-b^2
= (x+2)^2 - (y-1)^2 呢題只係調番轉咁解
= (x+2+y-1)[x+2-(y-1)]
= (x+y+1)(x-y+1)
5.
x^2y + 2xy +y
=y(x^2+2x+1)
=y(x+1)^2
6.
x^2y + 2xy +y - y^3
=y(x+1)^2-y^3 ---------呢題上半部同第5題一樣,so直接寫果part
=y[(x+1)^2-y^2] 既解法..略去左step
=y[(x+1+y)(x+1-y)]
7.(a-b)^2 - (a-b)^2
= 0 ---------兩個數一樣相減..唔駛計都知係0啦?定係打錯左?-.-
希望你明得哂呢7題既solution啦@@
2008-06-16 18:19:57 補充:
其實我唔太明因式分解係將
x^2 - y^2 轉做 (x+y)(x-y)
定係
(x+y)(x-y)轉做x^2 - y^2
我見到你呢7題好似兩種形式都有...
呢part唔駛理佢-.-做完我都明咩叫因式分解.事關我讀英中的..