Here's the question you clicked on:
liliy
concentrationn of salt x is given as funcion of time: dx/dt= 37.5-.35 x what is the salt concentration after 3 min?
So evaluating the derivative at a specific point. What part is it you do not get?
i jsut dont undertand what i need to do
Well, it is the whole momentary aspect of derivatives. They help find a value at a specific point in time. I'll see if I can find a good reference. I got caught up in a matrix qustion at the moment.
Are you going over anti-derivatives at this point? Hmm... Normally the derivative is the rate of change at a point, not what something is at that point. So I am wondering if you need to integrate this first.
This is either really simple, you need to put 3 in for x and solve, or slightly less simple you need to integrate it and put in 3. It all depends on where you are in studying math. Sort of gives a context for the problem.