Answer
See answer below.
Work Step by Step
a) A first-order differential equation can be written as: $f(x,y)=\dfrac{dy}{dx}$
where, $f(x,y)$ represents a function of two variables and is defined on a region in the XY-plane.
b) A solution is a function $y=f(x)$ that satisfies the first-order differential equation $f(x,y)=\dfrac{dy}{dx}$ when the function $f(x)$ and its first-order derivative are plugged into the equation.
