Maths. Questions

細薯

This is some questions in my Summer Vacation Exercise

Factorize:

(a)  2x^2 + 3xy + y^2

(b)  3p^2 - 7pq - 6q^2

(c)  5a^2 + 7ab + 2b^2

(d)  4c^2 + 4cd - 24d^2

*  c^2=c的二次方

help me please~

[ Last edited by smallpotato226 on 2004-8-30 at 10:22 AM ]

Echo21

smallpotato226  在 2004-8-30 09:12 發表:

This is some questions in my Summer Vacation Exercise

Factorize:

(a)  2x^2 + 3xy + y^2

(b)  3p^2 + - 7pq - 6q^2

(c)  5a^2 + 7ab + 2b^2

(d)  4c^2 + 4cd - 24d^2

*  c^2=c的 ...

最差的就是Factorization.....
D：
4(c^2+cd-6d^2)
是不是這樣？？

WZero

(a)  2x^2 + 3xy + y^2 = (2x+y)(x+y)

(b)  3p^2+ - 7pq- 6q^2 = (3p+2q)(p-3q)

(c)  5a^2 + 7ab + 2b^2 = (5a+2b)(a+b)

(d)  4c^2 + 4cd - 24d^2 = 4(c^2 + cd - 6d^2) = 4(c+3d)(c-2d)

rogergeot

(a).   2x^2+3xy+y^2
     =(2x+y)(x+y)
(c).   5a^2+7ab+2b^2
     =(5a+2b)(a+b)
(d).  4c^2+4cd-24d^2
     =(2c-4d)(2c+6d)
     =2(c-2d)2(c+3d)
     =4(c-2d)(c+3d)

I do not know what do you mean by +-7pq in question b.
Too bad someone answer the question faster than me... I was typing too slow.

[ Last edited by rogergeot on 2004-8-30 at 10:15 AM ]

細薯

i have got some mistake~
corrected

Echo21  在 2004-8-30 09:57 AM 發表:
最差的就是Factorization.....

我也是.....

+++++++++++++++++++++++++++++++++

after i read the answer above,
I remember the method to do la~~

thx every body~~

PS:我D功課只下50page maths ja~~~要繼續努力~~

thx a lot~

[ Last edited by smallpotato226 on 2004-8-30 at 10:26 AM ]

Echo21

rogergeot  在 2004-8-30 10:14 發表:

(a).   2x^2+3xy+y^2
     =(2x+y)(x+y)
(c).   5a^2+7ab+2b^2
     =(5a+2b)(a+b)
(d).  4c^2+4cd-24d^2
     =(2c-4d)(2c+6d)
     =2(c-2d)2(c+3d)
     =4(c-2d)(c+3d)

I do not know what do you  ...

可否詳解一下
不太懂
（死得，還要讀A.MATH）

rogergeot

Well.. I am not good at maths... but I will try my best...
Usually when we do factorization, for example: a)  2x^2 + 3xy + y^2, the answer should be something like: ? (?x add or subtract ?y)(?x add or subtract ?y). (like the answer in a)
We first list out all of the factors of 2x^2 and y^2 first:
Factors of 2x^2: 2x and x, -2x and -x
Factors of y^2: y and y, -y and -y
Then, we try to times and add the combination of factors which would give the result of 3xy:
2x times y add x times y = 2xy+xy = 3xy
So, the answer should be (2x+y)(x+y).

I hope that my explanation would not confuse you more.

抹茶可樂

我好懶的…做暑期作業果陣一定用cal計出來

yat

F.2上學期數黎

oscar

yat  在 2004-8-30 22:55 發表:

F.2上學期數黎

下？我要form3先教...不過我一早識~
奇怪既就係，點解大家唔用交叉法黎搵？