Answer:
See below
Explanation:
With the information given, we only need to find the value of the parameter c1 for which the initial condition holds. Assume our solution is of the given form

Then

Thus
. Therefore, the unique solution to the initial value problem is the function

Again, it's important to note that the problem gives us the general solution for granted. If you want to solve another IVP, sometimes you need to find the general solution first, and then find the parameters corresponding to the initial conditions.