In Section 5.3, you are asked to find the rate in a sinking fund. Using the ordinary annuity formula results in an equation that is very difficult to solve. Instead, try graphing each side to the equation and locating the point of intersection.
In many investment problems, you are given an amount of money and asked what will it accumulate to in a certain amount of time at some interest rate. Essentially, these problems are asking you to find the future value of the amount of money. Depending on how that money accumulates, you might use one of several different formulas.
The MathFAQ below looks at how you calculate present value in the context of different type of interest.
It is easy to confuse the processes for solving for the rate versus the number of years in the compound interest formula. The two MathFAQs compare the process of solving for the rate (using roots or powers) with solving for years (using logarithms)
The basic algorithm for solving a standard minimization problem is covered in Section 4.3. This process, called the Simplex Method, uses matrices and row operations to gauge whether an objective function is maximized at corner points.
In the example below, I write out a standard maximization problem from an application and then solve it with the Simplex Method.