Can some people add me as a friend cuz y account got deleted

Hashtags serve to identify the topic of a given tweet true false

When is a chart legend used a. all the time b. whenever you are comparing data that is the same c. whenever you are comparing multiple sets of data d. only for hand-drawn charts

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.