Please help, thanks! (simple question) I'm doing a project and need to ask two people what they think is the highest contributor to global warming. my phone is dead. What do you think is one of the greatest contributors to global warming? I have to make an app about the two things.

For positive constants a and b, the force between two atoms in a molecule is given f(r) = −a r2 + b r3 , where r > 0 is the distance between the atoms. note: a and b are upper case letters. (a) find f '(r) = (b) find the critical point for f(r). r = (c) find f ''(r) = (d) find the value of r so that f ''(r) = 0.