We all know that linear algebra has a fundamental identity. It’s ∑ fi = 0, which is really the only equation you need to know for linear algebra. But what does it mean? What are these symbols? In this blog post, I am going to explore some of the ways in which we can think about and understand this fundamental identity.
The symbols in this equation are: ∑ and fi. The symbol ∑ is called a “summation sign” and the symbol fi (or i) is an index or variable that takes on different values, depending on what kind of summations we’re doing. In general, it means to sum up all instances of the letter after the equal sign for each instance of the letter before it (+). So, if I wanted to make sure there were no zeros anywhere in my sentence above, I would just replace every zero with ei = 0 because both terms are expressions where e can take on any value as long as they do not add up to be zero. If you want more information about how indices work