Today we begin to study the connection between things we draw (geometry) and equations that describe them (algebra). This connection is possible because of the simple but brilliant idea of plotting points — here is a review of plotting.
In this class, we will focus on equations of lines. An equation of a line, or linear equation, is an equation that can be written in the form Ax+By=C, called standard form. Another useful form of linear equations that you may be familiar with is y=mx+b, or slope-intercept form.
There are a lot of resources available on the internet and elsewhere about equations of lines. Here are a few, grouped according to the major topics and types of problems.
We begin with an equation of a line, and draw the graph by finding solutions and plotting points.
One of the key pieces of information that we use in studying lines is the slope. If you need a review of finding the slope of a line, here is a video with a good explanation.
We will be practicing finding equations for lines. These types of problems can vary a bit depending on what information you are given at the start. The following series of videos cover several of the possibilities.
1. Find equation of a line based on the slope and one point (the y-intercept): http://youtu.be/AqFwKecNaTk
2. Find the equation of a line based on the slope and a point (not the y-intercept):
3. Find the equation of a line based on two points: http://youtu.be/XMJ72mtMn4Y