1. The problem statement, all variables and given/known data dT/dt = -k(T - T_m) T is the temperature of the body, T_m is the temperature of the surroundings, -k is some contant and t is ofcourse time 2. Relevant equations no idea 3. The attempt at a solution I tried solving this using first order linear ODE integrating factor method: so in standard form it can be written as- T' + kT = T_m let p(t) = k then u(t) = exp(∫ k dt) u(t) = exp(kt) we can forget about the constant. so multiplying ODE throughout by u(x) : exp(kt)*(T' + kT) = exp(kt)*(T_m) integrate both sides exp(kt)*T = [exp(kt)*(T_m)]/k divide both sides by u(t) T = (T_m)/k my book says this is wrong, why?