The Akra–Bazzi method is a way of quickly finding solutions to equations with a specific form called Recurrence Relation. This method can be used to quickly solve equations like "If x[1] = 4, and x[n] = x[n-1] + 2 for all n, what is x[4]?".
To use the Akra–Bazzi method, you must first identify if your equation is a Recurrence Relation. Then you must figure out two numbers - a and b - that describe the equation. To do this, find the first two values of the equation and solve for a and b. For example, if the equation starts with x[1] = 2 and x[2] = 4, we can say a is 2, and b is 2 (since 4 - 2 = 2).
Once you have a and b you can use the Akra–Bazzi method to quickly solve the equation. To do this you split the equation into two parts - the initial value part, and the recurring part. The initial value part will be x[1] = a, and the recurring part will be x[n] = ax[n-1] + b. This will give you a formula that you can use to quickly solve for any x[n] in the equation. So in our example, if we want to find x[4], we can use the formula x[4] = a*x[3] + b, and plug in the values of a (2) and b (2). This gives us 4 = 2*x[3] + 2, so x[3] = 2, and therefore x[4] = 4.