# Algebra

## Why We Care About “Why”

(Archive question of the week) One day back in November, as I entered the community college where I teach, a man came in behind me with his son, probably about 3 years old. It was the first snowy day of the year, and the father stood on the mat wiping his feet, while the little …

## How to Find an Inverse Function: Conflicting Approaches

While pondering issues that often give students trouble in algebra, I decided to check what we have said in Ask Dr. Math about inverse functions. I discovered four answers (all, as it happens, written by me – I tend to be attracted to certain topics!) to essentially the same question, spread over 13 years. It …

## Why Can’t You Divide by Zero?

Last time, I talked about students’ difficulties carrying out divisions that involve a  zero, which  reminded me of another issue that sounds almost the same, but is quite different: division of a number by zero. Students often either forget the rule they were taught, or they don’t believe the rule, or they just wonder about …

## A Sample of Ask Dr. Math, Part 1: Questions from School

In its more than 20 years, we answered hundreds of thousands of questions on Ask Dr. Math, only a small fraction of which were archived for public access. Those that did not make it into the archive were not bad answers, just not deemed to be of broad enough interest, or unique enough, to be …