Functions is an important concept in mathematics to grasp. These sites, blogs and videos do an excellent job of explaining it visually and offer all these videos and more resources for free. Hope this ...

https://doi.org/10.4169/college.math.j.42.4.283 https://www.jstor.org/stable/10.4169/college.math.j.42.4.283 Summary Finding the sum of a series in the form of a ...