F(x)=2g (x)+ 1 and g (x) is the odd function on R, then

f(-x)=-2g(x)+ 1

f( 1)=2g( 1)+ 1

f(- 1)=-2g( 1)+ 1

f( 1)+f(- 1)=2

f( 1)=2-f(- 1)=-6

2. let x < 0, then -x > 0.

∵ When x >; 0，f (x) = x 2-2x。

∴ f (-x) = (-x) 2-2 (-x) = x 2+2x =-f (x) ... (∵ f (x) is odd function)

∴f(x)=-x^2-2x

Therefore, the analytical formula of f(x) on R: f (x) = x 2-2x...x > 0.

-x^2-2x……x