Introduction to Differential Equations - Rhea

When I was first learning differential equations myself, I felt hard to understand the textbook and my lecture notes. After winning the battle, now I am trying to build up those concepts again and explain them in an easier and more concise way. It is not that academic, aiming for intuitive understanding.

1.1 Concept

Previously, we learnt to solve equations with numbers as solutions. For example, for linear equations ax+b=0 with respect to x and a≠0, the solution is going to be -\frac{b}{a}

For quadratic equations  with respect to x and a≠0, the solution is going to be .