Folder Contents: 

  Grapher.app is built into Apple's OS X. It can be found in the /Applications/Utilities subfolder of the /Applications folder.

  001 this document which is mainly a placeholder 

  A single linear equation in three variables determines a plane in 3-space. The solution to a system of three such equations determines three planes and the solution to the system determines the intersection of those planes.

  002 We expect three planes to intersect in a point. That is, we expect a unique solution (10,10,-8) to the system. 
  003 We say the system is overdetermined if there are too many equations in the sense that they have no common solution. In the typical overdetermined system of three equations in three unknowns, the three lines given by intersecting two of the planes are parallel.
  004 We say the system is underdetermined if there are too few equations in the sense that they have infinitely many common solutions. In the typical underdetermined system of three equations in three unknowns, the lines given by intersecting any two of the planes is containing in the third.

  005 The best fit line through the points (-1,1), (0,5) & (1,3) is shown.
  006 A geometric representation of the normal equations for the same problem is shown. The plane consists of all points whose coordinates are the y-coordinates of three points on a line in the plane with x-coordinates -1, 0 & 1. The point (1,5,3) is not on the plane because there is no line through the points in the plane. (2,3,4) is the closest point on the plane to (1,5,3). (2,3,4) corresponds to the line y=x+3 which passes through (-1,2), (0,3) & (1,4).

  007 This graph shows the unit circle, the ellipse obtained by applying the 2x2 matrix with rows [3 1] and [1 3] to the unit circle, and the lines in the directions of two eigenvectors. The eigenvalues are 4 & 2.

  008 This is an example of the derivative as a function. Note that there is a Differentiate option under the Equation tab.
  009 What are the functions whose graphs are on the cover of Quick Calculus?

  010 a zoo of the graphs of functions in two variables