This is quotes from online pdf files from University of Toronto Scarborough.

"the terminal velocity is F/b , where b is drag constant

Let’s solve the equation of motion and see how

this is reflected in the solution. Newton's law

reads

m (dv(t)/dt) = F - b v(t)

which we have written entirely in terms of the

velocity v(t) and its first derivative.

How to solve this? Well, if F were zero, we

would have dv/dt=–(b/m)v, which has its solution

some constant times exp(-bt/m). By inspection,

we find that we can account for nonzero F by

simply adding a constant, F/b. That is,

v(t) = F/b + (constant)exp(-bt/m)

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Now what i dont understand is the last paragraph, and where the last equation came from. Can anyone explain more clearly? Please help Thank you very much.