A linear equation is an equation of the form ax+by+c=0 which represents a straight line. Naturally the the variables are in degree one.
Examples: (1) y=x astraight line passing through the origin.
(2) y=2x+5, is a sraight line with slope 2 and intercepts -5 on x axis and 5 on y axis.
An equation of higher degree:
Any equation with variable x and y of higher degree does not represent a stight line.
Example:x^2+y^2 =1 is a circle. y^2=4x is a parabola.
Graph:The graph is a drawing on the graph sheet representing an equation (of straight line or circrle or any curve), whose coordinates should satisfy that equation (or relation).It gives a visual idea about how acurve behaves.
A quadratic equation in x is any equation with a degree 2. Or the highest degree of x among ithe terms has degree 2.
Example:(1) 5x^2+7x=10. (2) x^2 = 13.
Table: A table is a set of values listed satisfying a relation or to identify areltion between two charastics or variable:
Example: x^2+y^2 =25. To identify the reation interms quantities or to find the particular value for y given a x value we prpare a table. It helps us tplot the graph of the curve also: We list below some values satissfying x^2+y^2=25.