use the definition of the derivative to compute the derivative of the function at x=1 f(x) = 1/(1 + x 2) for all x. 3. The attempt at a solution i put it into lim[ (f(x)-f(xo))/x-xo ] form and got [(1/1+x2) - (1/2)] <---------numerator ___________________________ <----- division sign ("over") x-1 <----------- denomenator form and from there cancelled to 2-1-x2 / 2(x2+1) and then again to -x2 + 1 / 2(x2+1) but now im stuck and cant find a cancellation to calculate the limit at x=1 without getting a 0 in there soemwhere if i stick this into the limit calculation formula itll just give me a 0 and thats no good. i already know the answer is -1/2 but i cant quite get there. any help is appreciated, thanks.