There are some relationships but not all relationships are always true. Any function can be represented by an equation. But all equations are not functions. For example, y = sqrt(x) is the equation of the square root relationship which can be graphed as a parabola on its side, but it is not a function. It has slopes at each point. Some functions can be plotted as graphs but not all. A function such as f(x) = 1 when x is rational, and f(x) = 0 when x is irrational has no slope and cannot be plotted as a graph. A graph of a vertical line is not a function.
A linear function is any function that graphs to a straight line. What this means mathematically is that the function has either one or two variables with no exponents or powers. If the function has more variables, the variables must be constants or known variables for the function to remain a linear function.
A title, labeled axes (for graphs), markings on the axes (again, for graphs) and units of measurement. You could use any of the above, based on your context
No, sorry. WikiAnswers does not use graphs, pictures or diagrams.
No, not all chords of a circle pass though the center of that circle. Any cord that does pass through the center of the circle is called diameter of that circle.
Actually, they are useful. At least in some cases.
There is no specific collective noun for a group of graphs, in which case any noun that suits the context can be used; for example a pile of graphs, a display of graphs, a collection of graphs, etc.
The center of a circle is the same for all circles but the length of the radius can change
There are infinite diameters in a circle all of the same lengths.
Restate question: What is an example of a non-function? The equation of a circle is x2 + y2 = r2. Since a function can only be intersected once by a vertical line, the circle is not a function (almost any vertical line through the circle will cut it twice). If you solve the equation for y, you must write: y = +/- sqrt(r2-x2), so for each value of x there are TWO values of y.
One circle is different from another only in radius or location. All circles are geometrically similar, meaning that you can translate and scale any circle onto any other circle.
The radius is always at a fixed, unchanging distance from the center of a circle to all the surrounding points.