中3數~高手~pls!

1. 2c^2-50
=2 (c^2-25)
=2 (c+5) (c-5)



2 3x-2y-7=0 ....(1)
5x+4y+3=0....(2)

(1) : 3x-2y=7
(2) ; 5x+4y = -3

(1) x 2 + (2) ,
(6x-4y ) + (5x+4y) = 2x7 -3
11x = 11
x=1
sub x=1 into (1)
3-2y = 7
-2y = 4
y= -2

圖片參考：http://img189.imageshack.us/img189/9293/screenhunter03jul082246.gif



http://img189.imageshack.us/img189/9293/screenhunter03jul082246.gif

2c^2-50
2(c^2-25)
2(c+5)(c-5)

f2
我味學聯立方程,幫唔到你!SORRY!

2010-07-08 16:19:32 補充：
3d^2-10
can not be factorized

a^3+1
(a+1)(a^2-a+1)

2010-07-08 16:21:23 補充：
identity(恆等色)
(a^3+b^3)
(a+b)(a^2-ab+b^2)

(a^3-b^3)
(a-b)(a^2+ab+b^2)

2010-07-08 16:22:35 補充：
I am f2....

2010-07-08 16:51:38 補充：
3c^3-81
3(c^3-27)
3(c-3)(c^2+6c+9)

b^3-8
(b-2)(b^2+2b+4)

a^3b^3+8
(ab)^3+2^3
(ab+2)(a^2b^2+2ab+4)

2010-07-08 16:51:55 補充：
a^3b^3+8
(ab)^3+2^3
(ab+2)(a^2b^2-2ab+4)