Solving 1D Motion Question with x>0, v<0, a>0

[mttal24]

Homework Statement

Give example of a motion where x>0, v<0, a>0 at a particular instant.
x-->Position
v-->Velocity
a-->Acceleration

Homework Equations

I thought I had to give an example such as a car, ball etc.
But the answer says:
x(t) ie; position for time t; given by
x(t)=A+Be^{-\gamma t}
where A>B, \gamma>0 are chosen +ve constants.

The Attempt at a Solution

I don't know how to do it. Please help.

 

[bigerst]

the given example wasnt the only solution

another example would be
x(t) = 3t^2 -20t+100 at t=2

for your example use calculus, for at t=1, x>0 as u can check
differentiate dx/dt = -γBe^(-γt), which is less than zero at t=1
differentiating again gives a=(γ^2)(B)(e^-yt) which is positive at t=1