教育學術 -math,help!!!!!!!!!!!!!

f(x) = x- x^2

f(1-x) = (1-x) - (1-x)^2 <---將1-x sub 入去x果度..

f(x) - f(1-x) = x - x^2 - [ (1-x) - (1-x)^2]

= x - x^2 - ( 1 - x -1 + 2x - x^2)

= x - x^2 - 1 + x +1 - 2x + x^2

= x^2 - x^2 + x + x - 2x + 1 - 1 <----呢步可以唔寫

= 0


=]

x- x^2 - (1 - x) - ( 1 - x) ^2
=x(x-1) - (1-x)(1-x)
= x(x-1) + (1-x)(x-1)
= (x+1-x)(x-1)
= 1(x-1)
= x-1

2008-03-20 19:03:03 補充：
x- x^2 - (1 - x) + ( 1 - x) ^2
= x(1-x) - (1-x)(1-1+x)
= x(1-x) - x(1-x)
= 0



上面那個是錯的，這個才是