Factorize果d 唔識T^T,幫下忙(20點)好急

1.
x(4abx - b²) + 4(ab - 4a²x)
= bx(4ax - b) + 4a(b - 4ax)
= bx(4ax - b) - 4a(4ax - b)
= (bx - 4a)(4ax - b)


=====
2.
2x(x - y + 3) - 5xz + 5yz - 15z
= 2x(x - y + 3) + (-5xz + 5yz - 15z)
= 2x(x - y + 3) - 5z(x - y + 3)
= (2x - 5z)(x - y + 3)


=====
3.
z = (1/x) - (6/y)
z + (6/y) = 1/x
1/x = (yz + 6)/y
x = y/(yz + 6)

2013-08-30 23:33:20 補充：
這也未必是 Kandy 分身投票，也可能是「朋友」多吧！

Yahoo+ 知識就是多這不健康的投票現象，一直本人與一些熱心的網友不時因失望而短暫離開這裡，甚至一去不返。

本人也不少次遇到類似的情況。

總之，答了便算吧。是否得到「最佳答案」，是「幼兒級」還是「知識長」，絕不會影響你本身的知識。

1. Factorize x(4abx-b^2)+4(ab-4a^2x)

x[4abx-(b^2)]+4(ab-4(a^2)x)<<<記得D n次方用括號,我睇得明唔代表人地會唔混淆
=4ab(x^2)-(b^2)x+4ab-16(a^2)x
=4ax(bx-4a)-b(bx-4a)
=(4ax-b)(bx-4a)

2. Factorize 2x(x-y+3)-5xz+5yz-15z

2x(x-y+3)-5xz+5yz-15z
=2x(x-y+3)-5z(x-y+3)
=(2x-5z)(x-y+3)

其實都係考你分組個能力
一開始見到D散terms有得group就group
冇就爆開哂再睇
記住正負號一定唔錯得!

如果你有心想識既
做多D 易既factorization練習
做數學書果d已經夠哂
1個月你就好快甘掌握到點抽,點做
係會好似機械人甘自動知道抽咩出來

3. Make the letter in the bracket the subject of the formula
Z= 1/x - 6/y (X)

Z=1/X - 6/Y
XYZ=Y - 6X
XYZ+6X=Y
X(YZ+6)=Y
X=Y/(YZ+6)

2013-08-27 01:06:26 補充：
Make...as subject...果D
如果有分數,就成條式乘左D分母佢
好似第3題
有X同Y分母
就成條式乘XY
姐係Z*XY=(1/X)*XY-(6/Y)*XY
--> XYZ=Y-6X
跟住就將有果個字母既野擺去左邊
冇果個字母擺去右邊
-->XYZ-6X=Y
(有X) (冇X)
下一步就抽果個字母出來
-->X(YZ-6)=Y
汁一汁位
--> X=Y/(YZ+6)
完成!

2013-08-27 01:11:29 補充：
我做第3題個方法未必最快,但係一定做到
如果條式冇1/X,你可能已經卡住用唔到上面佢地教你個方法
如果你未熟習就用住我呢個方法啦,因為題題都做得,只要冇2次方,3次方...etc
祝學業進步

唔該曬你>< 加深了記憶了現在><總算慢慢開始計到;)

Kandy, 勞煩上前補充回答芷晴。

1. x(4abx-b²)+4(ab-4a²x) = xb(4ax-b)+4a(b-4ax) = xb(4ax-b)-4a(4ax-b) = (xb-4a)(4ax-b)

2. 2x(x-y+3)-5xz+5yz-15z = 2x(x-y+3)-5z(x-y+3) = (2x-5z)(x-y+3)

Also, no offense, your final answer for Question 3 missed an important bracket.

Compare the meaning of a/b+c vs a/(b+c)

2013-08-26 22:47:08 補充：
Kandy, I also teach you one technique here.

z = 1/x - 6/y　<--- you see that out of 3 terms, only 1 term contains x.

1/x = z + 6/y　<--- put that term aside

x = 1/(z+6/y)　<--- I like teaching this step, multiply y to both numerator and denominator.

x = y/(yz+6)　<--- done! =^o^=

2013-08-26 23:36:41 補充：
不用客氣～

=^o^=

2013-11-13 21:30:35 補充：
多謝你地呀，土扁、Uncle Michael。

我到今日先有機會睇番呢個post。

我都覺得有Ｄ奇怪！！！

I just do no.3 for U .....

3. Z= 1/x - 6/y (x)
z=1/x-6/y
z=(y-6x)/xy
zxy=y-6x
zxy+6x=y
x(zy+6)=y
x=y/zy+6
by the way,I have some questions sent to yr email,could U pls check it out? :)

2013-08-28 19:24:05 補充：
Thank you 有禮貓,你根本就係Masterijk,仲咩轉個感動聽ge 名噢?!Ha!