Graphs are used to represent numerical information in a diagrammatic form. For example: in newspapers they are used to represent data in such a way that makes it easier for us to apprehend the decreasing or increasing trends. For example, population of various years can be represented on a graph sheet with the help of population data. Thus, graphs make it easier for us to convert raw data into meaningful information. One of the graphs used for these purposes is a line graph. In a line graph variation in the value of a quantity is represented with the help of a line. Line in the line graph is formed by joining various points which are donated by coordinates. Line graph containing line lying between fixed coordinates is known as linear graph.

__Location of point with the help of coordinates on a linear graph:__

__Location of point with the help of coordinates on a linear graph:__

We can locate a point on a linear graph with the help of its coordinates. Coordinates are nothing but the parameter used that tell us about the location of a point. Let us understand this with the help of an example. Suppose, you are sitting in a cinema hall, you need to tell your friend about your location. What will you do? You will tell him/her about the number of row and column corresponding to the place where you are sitting. Thus, in this case row and column number helps your friend locate your position. Similarly, in a linear graph we use two coordinates for locating a point. These coordinates are the X-coordinate and the Y-coordinate in a linear graph. Position of a point is thus represented as (x, y) where x is the X- coordinate and y represents the Y-coordinate. Let us try and locate points (2, 3), (8, 12), (6, 9) and see whether they lie on a same line on a linear graph.

The above graph represents the points located by us. Upon joining these points we obtain a line lying between these coordinates, thus the above graph is a linear graph.

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