(2). f (x) = (1+x) 2-ln (1+x) 2, take f'(x)=2+2x-2/( 1+x) and find f'(x). Then f (x) = x-2ln (1+x)+1-b is monotonic, and the derivative f'(x)= 1-2/ 1+x≠0, x ≠ 650. 0, f(2)>0, which brings these three conditions: 1-2LN2+ 1-b < 0,1-b > 0,2-2ln3+1-b > 0, and the solution is: b & gt2-2ln2, b< 1, b.