School math, multimedia, and technology tutorials.
FooPlot is an online HTML5 graphing calculator that supports graphing of polynomial, trigonometric, and hyperbolic functions. It can also be used in plotting piecewise functions, parametric functions, and polar graphs.
Graphs created with FooPlot are considered as public domain files. They can be exported as PDF, EPS, PNG, and SVG format. According to the author, embed codes will be provided soon.
A prime number is a integer greater than that is divisible only by 1 and itself. A number that is not prime is composite.
To determine whether a number is prime or not, we have to divide it by all numbers between 1 and itself . For example, to say that 257 is prime, we must be sure that it is not divisible by any number between 1 and 257. In this discussion, the word “numbers” refer to positive integers.
Are you prime or not?
Dividing a number by all numbers between 1 and itself is burdensome especially for large numbers. In this post, we discuss a shorter way of determining if a number is prime and explain why the method works. » Read more
In Proof of the Sum of Square Numbers, I have mentioned about proof without words. Some of you are probably wondering what they are, so I will discuss in detail.
Proof without words are diagrams or pictures that help readers see why a particular statement is true even without accompanying explanations. One example is a classic proof of the Pythagorean theorem shown in the first figure.
In the example, we have two congruent squares. There are four congruent right triangles occupying portions of both squares. It is clear that the total area occupied by the triangles in the first diagram is equal to the total area occupied by the four triangles in the second diagram. If the occupied areas on both squares are equal, it follows that the unoccupied areas are also equal (Why?). Therefore, 
Proofs without words cannot always be considered as “proof” in the formal sense. For instance, the second figure cannot be considered as a proof since only four cases are shown. The generalization of the figure shows that the sum of the first 
The formal proof of the equation can be demonstrated using mathematical induction.
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I am currently reading a collection of Proofs without Words by Roger Nelsen. You may want to check it out.