中二數學一問(7)

15.ax+ay-bx-by
=a(x+y)-b(x+y)
= (a-b) (x+y)
16.ay+bx-ax-by
=a(y-x)-b(y-x)
=(a-b)(y-x)
17.ax-y+x-ay
=x(a+1)-y(a+1)
=(x-y) (a+1)
18.2x(5a+2b)-6xy(5a+2b)
=(2x-6xy) (5a+2b)
18b.ax+3-3a-x
=a(x-3)-(x-3)
=(a-1)(x-3)
19.a(x-1)+b(1-x)
=a(x-1)-b(x-1)
=(a-b) (x-1)
19b.5x-6a-2ax+15
=5(x+3)-2a(x+3)
=(5-2a) (x+3)
20.x(a-b)-y(b-a)
=x(a-b)+y(a-b)
=(x+y) (a-b)
20b.3a-12ax+2-8x
=3a(1-4x) + 2(1-4x)
=(3a+2) (1-4x)
21.3(5-2a)-x(2a-5)
=3(5-2a) + x(5-2a)
=(3+x) ( 5-2a)
22.x(b-a)+y(a-b)
=x(b-a)-y(b-a)
=(x-y) (a-b)
23.a(x-3)+(3-x)
=a(x-3)-(x-3)
=(a-1) (x-3)
24.x-y-b(y-x)
=(x-y) – b(x-y)
=(x-y) (1-b)

15.=a(x+y)-b(x+y)
=(a-b)(x+y)
16.=a(y-x)+b(x-y)
17.=a(x-y)-y+x
18.=10xa+4xb-30axy-12bxy
18b.=a(x-3)+3-x
19.=ax-a+b-bx
=(a-b)x-a+b
20.=xa-xb-yb+ya
=a(x+y)-b(x+y)
=(x+y)(a-b)
20b,我唔識!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
21.=15-6a-2ax+5x
22.=xb-xa+ya-yb
=(x-y)b-(x-y)a
=(x-y)(b-a)
23.=ax-3a+3-x
=(a-1)(x-3)
24.=x-y-by+x
=2x-(b+1)y

做ed數首先要分類，好似第16 題咁，將ay ax 和 bx by放埋一齊，ay-ax+bx-by
然後就抽大家都有的東西: 大家都有a，就抽a : a(y-x)+b(x-y)
由於 y-x 和x-y 不同，不能抽，所以要整到相同，將+變-就可以: a(y-x)-b(y-x) 之後再抽=(y-x)(a-b)
所以之前幾個回答者全部錯曬!!!!!!!!!!
第17題有少少唔同
先分類: ax+x-ay-y 抽個陣要小心:抽左個x仲有個1係度，y都係
a(x-1)-y(a-1) 個答案就係咁
第18題再多一個步驟
(5a+2b)(2x-6xy) 由於(2x-6xy) 仲有得抽
(5a+2b)2x(1-3y) 不過唔知你個老師會唔會教你e個步驟
18b都一樣 分類: 3-3a+ax-x
抽: 3(1-a)+x(a-1)
轉符號: 3(1-a)-x(1-a)
再抽: (1-a)(3-x)
19a今次唔使分類，先轉符號: a(x-1)-b(x-1)
抽: (x-1)(a-b)
19b的難度再加一點，分類要小心d，分錯左會好麻煩，你見到5x同5個數好靚，就分佢地一齊，5x+15-6a-2ax
抽: 5(x+3)-2a(3-x)
轉符號:5(x+3)+2a(x-3)
(x+3)(5+2a)
20都好像19a咁計
20b同19b一樣
21同19a一樣
22同19a一樣
23同19a一樣
24多個步驟: b(y-x)+(x-y)
=b(y-x) -(y-x)
=(y-x)(b-1)



2007-12-08 20:16:51 補充：
其他人唔係跳步驟就係未抽完跳步驟老師會話你錯未抽完會當你未計完

15. ax+ay-bx-by
=a(x+y)-b(x+y)
=(a-b)(x+y)

16.ay+bx-ax-by
=ay-ax-by+bx
=a(y-x)-b(y-x)
=(a-b)(y-x)

17.ax-y+x-ay
=ax-ay+x-y
=a(x-y)+x-y
=(a+1)(x-y)

18.2x(5a+2b)-6xy(5a+2b)
=(2x-6xy)(5a+2b)

18b.ax+3-3a-x
=3-3a-x+ax
=3(1-a)-x(1-a)
=(3-x)(1-a)

19.a(x-1)+b(1-x)
=a(x-1)-b(x-1)
=(a-b)(x-1)

19b.5x-6a-2ax+15
=5x+15-2ax-6a
=5(x+3)-2a(x+3)
=(5-2a)(x+3)

20.x(a-b)-y(b-a)
=x(a-b)+y(a-b)
=(x+y)(a-b)

20b.3a-12ax+2-8x
=3a(1-4x)+2(1-4x)
=(3a+2)(1-4x)

21.3(5-2a)-x(2a-5)
=3(5-2a)+x(5-2a)
=(3+x)(5-2a)

22.x(b-a)+y(a-b)
=x(b-a)-y(b-a)
=(x-y)(b-a)

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

24.x-y-b(y-x)
=x-y+b(x-y)
=(1+b)(x-y)
順便告訴你：應該是17.ax-y+x-ray，不是ax-y+x-ay，所以我不一定對~

15. (a-b)(x+y)
16. (a-b)(y-x)
17. (x-y)(1+a)
18. (2x-6xy)(5a+2b)
18b. (x-3)(a-1)
19. (a-b)(x-1)
19b. (5-2a)(x+3)
20. (x+y)(a-b)
20b. (3a+2)(1-4x)
21. (5+2a)(3+x)
22. (x-y)(b-a)
23. (x-3)(a-1)
24. (x-y)(1-b)

15. ax+ay-bx-by
=a(x+y)-b(x+y)
=(a-b)(x+y)

16.ay+bx-ax-by
=ay-ax-by+bx
=a(y-x)-b(y-x)
=(a-b)(y-x)

17.ax-y+x-ay
=ax-ay+x-y
=a(x-y)+x-y
=(a+1)(x-y)

18.2x(5a+2b)-6xy(5a+2b)
=(2x-6xy)(5a+2b)

18b.ax+3-3a-x
=3-3a-x+ax
=3(1-a)-x(1-a)
=(3-x)(1-a)

19.a(x-1)+b(1-x)
=a(x-1)-b(x-1)
=(a-b)(x-1)

19b.5x-6a-2ax+15
=5x+15-2ax-6a
=5(x+3)-2a(x+3)
=(5-2a)(x+3)

20.x(a-b)-y(b-a)
=x(a-b)+y(a-b)
=(x+y)(a-b)

20b.3a-12ax+2-8x
=3a(1-4x)+2(1-4x)
=(3a+2)(1-4x)

21.3(5-2a)-x(2a-5)
=3(5-2a)+x(5-2a)
=(3+x)(5-2a)

22.x(b-a)+y(a-b)
=x(b-a)-y(b-a)
=(x-y)(b-a)

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

24.x-y-b(y-x)
=x-y+b(x-y)
=(1+b)(x-y)

希望可以幫到你=]

15. =a(x+y)-b(x+y)=(x+y)(a-b)#

其它自己做LA
慢慢做就識