R is a set of real numbers. A function f from R into R is given by f(x)=x/(x^2 +1).

Show that if a and b are real numbers with a>b>=1, then f(b) -f(a)=((a-b)(ab-1))/((1+a^2)(1+b^2))

well, I felt kind of confused here, as I thought I just have to do the sum, but then what's the point of providing "a>b>=1"?

And, deduce that f(b)>f(a)

same here, I thought that was pretty obvious. How should I deduce it???