# Finding an undefined limit by substitution

In electrical engineering, you’ll need to find the rates at  which alternating currents and voltages are changing.  In financial  applications, you may want to calculate the rate at which continuously  compounded interest is growing.  And in healthcare, you might need to  calculate the rate at which per capita costs are rising, where the total  costs and the patient population are both functions of time.

In short, you’ll need to know how to differentiate  trigonometric, exponential, and logarithmic functions, as well as the  products and quotients of functions.

Finding an undefined limit by substitution

• Find a resource with a tutorial/ information that will help you  create a specific, original, math problem related to your topic.   Remember,   you are NOT teaching the whole topic, but just how to solve ONE PROBLEM you’ve created.    You  must cite your source in APA format.  (Even if you know how to create  and solve a problem related to your topic, you still must include a  source that your classmates can reference, to read more about what you  are teaching.)
• Tell us the problem you’ve created.  Remember, your problem must be ORIGINAL: made up by YOU. DO NOT  use a problem that has a full solution from a resource.
• Tell us how to solve your problem step by step.  Your solution  should include all mathematical steps as well as explanations in your  own words.  You can type this with the equation editor right here in the  reply box, you can use an image file to show hand-written work, or you  can make a video using the media tool to provide your explanations!  I  encourage you to get creative with how you explain your solution!