maths(only one)

(x-y)+(y-z)+(z-x)
= x – y + y – z + z – x
= x – x + y – y + z – z
=0

1. (x-y)+(y-z)+(z-x)
= x-y+y-z+z-x
= x-x-y+y-z+z
= (-y)+y-z+z
= -z+z
= 0

2. (5y的2次方+x-3z)+(2z-5x)-(4z-6y的2次方)
= 5y的2次方+x-3z+2z-5x-4z+6y的2次方
= 5y的2次方+6y的2次方+x-5x-3z+2z-4z
= 11y的2次方-4x-5z
(^_^)

(x-y)+(y-z)+(z-x)
=x-y+y-z+z-x
=0

將括號整走先...負負得正...正正得正...正負得負....
之後減哂佢....就會等於"0" lor~!!!

2006-10-31 21:06:09 補充：
就會等於"0"

(x-y)+(y-z)+(z-x)
=x-y+y-z+z-x
=(x-x)+(-y+y)+(-z+z)
=0+0+0
=0

(x-y)+(y-z)+(z-x)
=x-y+y-z+z-x
=0

2006-11-02 19:57:53 補充：
(5y的2次方 x-3z) (2z-5x)-(4z-6y的2次方)= 5y的2次方 x-3z 2z-5x-4z 6y的2次方= 5y的2次方 6y的2次方 x-5x-3z 2z-4z= 11y的2次方-4x-5z

(x-y)+(y-z)+(z-x)
=x-y+y-z+z-x
=0

2006-10-31 20:57:56 補充：
下面個個錯嫁!!!