幾條因式分解既數唔識做(急急急)20分

1. x(2) - x+3x-3

Sol: x^2 - x + 3x - 3

....= x( x-1 ) + 3( x-1 )

....=( x-1 )( x+3)

2. x(2)-2c-2x+cx

Sol: x^2 - 2c -2x + cx

...= x^2 - 2x + cx - 2c

...= x( x-2 ) + c( x-2 )

...=( x-2 )( x+c )

3. 6p(2)-4p -9p

Sol: 6p^2 - 4p - 9p

...= 6p^2 - 13p

...= p ( p - 13 )

4.cd(2)-c(2)d-c+d

Sol: cd^2 -c^2 d - c + d

...= cd ( d-c ) + ( d-c )

...= ( d-c )( cd+1 )

2008-12-02 22:54:06 補充：
Sorry!! Sorry!! 題3 有少少需要更正!!

3. 6p(2)-4p -9p

= 6p^2 - 13p

= p (6p - 13)

1.
x²-x+3x-3
x²-2x-3
=(x-3)(x+1)

2.
x²-2c-2x+cx
=x(x-2)+c(x-2)
=(x-2)(x+c)

3.
6p²-4p-9p
6p²-13p
=p(6p-13)

4.
cd²-c²d-c+d
=d(cd+1)-c(cd+1)
=(cd+1)(d-c)

1.

x^2 - x+3x-3
=x(x-1)+3(x-1)
=(x-1)(x+3)


2.

x^2-2c-2x+cx
=(x^2-2x)+(cx-2c)
=x(x-2)+c(x-2)
=(x-2)(x+c)

3.

6p^2-4p -9p
=6p^2-13p
=p(6p-13)

4.

cd^2-c^2d-c+d
=(cd^2+d)-(c^2d+c)
=d(cd+1)-c(cd+1)
=(cd+1)(d-c)

1.
x2 - x+3x-3
= x2 + 2x - 3
Using Cross Method
= (x + 3)(x - 1)


2.
x2- 2c - 2x + cx
= x2 + cx - 2c - 2x
= (x2 + cx) - (2c - 2x)
= x(x + c) - 2(c + x)
= (x + c)(x - 2)


3.
6p2 - 4p - 9p
= 6p2 - 13p
= p(6p - 13)


4.
cd2 - c2d - c + d
= (cd2 - c2d) - (c - d)
= cd(d - c) - (c - d)
在 d - c 中，抽 -1 為 Common Factor ，使它們便為 c - d
= -cd(c - d) - (c - d)
= -(c - d)(cd + 1)


如果唔識計 Cross Method ，你先去睇下啦。


http://hk.knowledge.yahoo.com/question/question?qid=7008100802140

計時!
1=x(x-1) 3(x-1)
=(x-1)(x 3)

2=x(c x)-2(c x)
=(c x)(x-2)

3=6p^2-13p
=p(6p-13)

4=d(cd 1-c(cd 1)
=(cd 1)(d-c)

2次方= ^2
有d 重新換位的數不作式論
第3題有問題?(共79秒)