1. The problem statement, all variables and given/known data Need to calculate fractional uncertainty f, of M (mass of a star in this case), where f is much less than one. The hint i was given was all i need to know is M [tex]\alpha[/tex] d3, and use a taylor expansion to the first order in f. M = mass of a star, d = distance to star 2. Relevant equations M [tex]\alpha[/tex] d3 3. The attempt at a solution Firstly, im stuck at what the [tex]\alpha[/tex] means, ive never seen it used before in this sense, at least not that i remember. Cut and paste shows it to be a division sign, although that doesnt mean much. Im not very strong with taylor expansions at all. Assuming that the [tex]\alpha[/tex] is supposed to be a division sign... f(x) = M/d3 then... f(a) + (f`(a)/1!)(x-a) then... M/d3 + 1/d3(x-a) would be the first order? Im guessing you take the derivative with respect to M. Would 1/d3 be my uncertainty since that is the first order? Its been awhile since i worked on taylor expansions and im very confused.