# Month: January 2019

## Significant Digits: Operations

Last time, we introduced what we mean by significant digits (or figures), and touched on why they are defined as they are. Here we will look at how significant digits and decimal places differ, and how they are affected by operations (primarily addition and multiplication). This is another aspect of why they are defined at …

## Significant Digits: Introduction

Our next series of posts will be about the concept of significant digits (also called significant figures), which are important in scientific or engineering calculations to keep track of the precision of numbers (although, as we’ll see, they are not what you would use when you need to be especially careful). We’ll start with the …

## Graphing Transformed Sines

I’ll close out our look at transformations of functions with some trigonometric graphs. These are the best example of combined transformations, and involve some special tricks as well. We’ll start with an early question that gives an overview of the process, then focus in on important details. Overview First, a typical question from 1997, to …

## Absolute Value Transformations: Inside or Out

Having looked at all the usual transformations of a function and its graph, there are two more situations I want to look at. The first of these are the horizontal and vertical transformations introduced by absolute values (with a bonus thrown in: square roots); then next time we’ll conclude this series with a look at …

## Finding Transformations from a Graph

(An archive question of the week) We’ve looked at the basic transformations of a function and how they affect its graph, then at how they combine, and then how they can interact with specific functions. Now let’s look at one problem from beginning to end, looking at a graph and finding the function that goes …

## Equivocal Function Transformations

The last two posts were about transformations of functions (shift, stretch, reflect) and their effect on a graph, first individually and then in combination. The next thing to look at will be how to determine the transformations when you are given a graph; but before we take that challenge in general, we need to see …

## Combining Function Transformations: Order Matters

Last time we looked at questions about how to shift, stretch, or flip a graph by changing the equation of a function. All our examples involved only a single transformation. Now we can look at cases where two or more transformations are combined. As we do this, we will develop a deeper understanding of how …

## Shifting and Stretching Graphs

A common topic in algebra courses is how to transform functions and their graphs. In the series starting today, we’ll start with the basics of how and why a graph is moved or stretched, then combine transformations and look at various special cases and other transformations, ending up with graphing trigonometric functions. Translating (shifting) a …

## What It Takes to Be a Math Doctor

In the Ask Dr. Math service, new volunteers went through a period of training (“internship”), first demonstrating their ability to write effectively about math with some example problems, and then answering actual questions under supervision, discussing their answers with a mentor online before they were actually sent out. Once our reliability was confirmed, we were …