a sphere with radius of 1meter has a temp = 15degrees. It lies inside a concentric sphere with radius of 2meters and temp = 25degrees. The temp T(r) at a distance r from the common center of the spheres satisfies the differential equation
(d^2T)/dr^2 +(2/r)(dT/dr) = 0
if we let S=dT/dr then S satisfies a first order differential equation. Solve it to find an expression for the temperature T(r) between the spheres.
I do not understand where the integrating factor came from, and I also do not understand how you jumped from to
if you would please explain these further that would be great. Also i do not understand why my post was moved out of calculus section, because this is only a calc2 problem, so perhaps this math is higher than my current level