I'll give you the solution to b, you try to work to that end. Okey-doke?.
b):
Originally Posted by simfonija
Multiply by "x",
This is a Linear-First Order Differential Equation.
Here,
Therefore,
Thus, the solutions are,
Thus,
Use, ,
Now you probably mean,
because these are usually how initial conditions are given.
Thus,
From here the unique solution is,