1. The problem statement, all variables and given/known data Let f(t) be the weight (in grams) of a solid sitting in a beaker of water. Suppose that the solid dissolves in such a way that the rate of change (in grams/minute) of the weight of the solid at any time t can be determined from the weight using the forumula: [tex]f'(t) = -4 f(t) ( 5 + f(t) )[/tex] If there is 2 grams of solid at time t = 2 estimate the amount of solid 1 second later. 2. Relevant equations [tex]f'(t) = -4 f(t) ( 5 + f(t) )[/tex] 3. The attempt at a solution So I get [tex]f'(2)=-56[/tex] Not sure what to do after that, do I use a differential?