(2) because f (x) = log2 [(2/1-x)-1] = log2 [(1+x)/(1-x)]

= log2( 1+x)-log2( 1-x)

f(-x)= log2[(2/ 1+x)- 1]= log2[( 1-x)/( 1+x)]

= log2( 1-x)-log2( 1+x)

So F(-x)=-F(x), so F(x) is odd function.