As I had ever know there are at least two (previously unsolved) problems motivate the study/development of abstract algebra: (1) the ancient Greeks' three problems in compass-and-straightedge construction, and (2) the problem of solving polynomial equations of degree five or higher.
Although to me it is fascinating to study mathematicians' insights into these kind of problems, I haven't understand clearly what (previously and currently unsolved) problems motivate the study/development of analysis.
Could someone please explain like you are teaching a math undergraduate with some mathematical maturity? Thanks in advance!