1. The problem statement, all variables and given/known data I have E(v) = (m*c^2)/sqrt(1-v^2/c^2). I also have a second-order Taylor-polynomial around v = 0, T_2_E, which is mc^2+½mv^2. I have to use Taylors formula with restterm to show that E is bigger than T_2_E for all v in the interval [0,c). 3. The attempt at a solution I have written an expression: E(v) = T_2_E + 1/n! * int [E'''(t)*(v-t)^2] dt, where n of course is 2, so it's 1/2 infront of my integral. I am very uncertain whether my expression is correct or not - do I have to use the limits 0 to c, or 0 to v? Thank you in advance.