National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Standard Form of a Line
Dr. Math gives an inspiring and clear discussion about equations of lines and lines as functions. The Dr. discusses the benefits of the standard form of a line and prompts the student with an equation which can not be written in the...
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Equation for Undefined Slope
This site gives the equation for a vertical line which passes through 8 on the x axis. The Dr. explains why the equation is what it is by giving a more general equation for a line than y = mx + b.
Other
Math N Stuff: Vertical Lines
This site gives information regarding vertical lines. The site contains a graph and poses a question relating to the equation of the line on the graph. The correct answer may be clicked on with a short reason.
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: Equation of a Line Parallel to an Axis
Dr. Math gives a short discussion on how to find the equation of a line parallel to an axis (, parallel or horizontal.)
National Council of Teachers of Mathematics
The Math Forum: Ask Dr. Math: When Is a Slope 0 or Undefined?
At this site Dr. Math gives a discussion on the slopes of lines. The Dr. gives an analogy between the slope of a line and walking up and down hills. The Dr. explores the concept of undefined and zero slopes through his response to a...