Linear Graph


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Linear Graph

Linear means straight and a graph is a diagram which shows a connection or relation between two or more quantity. So, the linear graph is nothing but a straight line or straight graph which is drawn on a plane connecting the points on x and y coordinates. We use linear relations in our everyday life, and by graphing those relations in a plane, we get a straight line.

Now that you have got an introduction to the linear graph let us explain it more through its definition and an example problem.

Linear Graph Equation

As discussed, linear graph forms a straight line and denoted by an equation;


where m is the gradient of the graph and c is the y-intercept of the graph.

The gradient between any two points (x1, y1) and (x2, y2) are any two points on the linear or straight line.

The value of gradient m is the ratio of the difference of y-coordinates to the difference of x-coordinates.

i.e. m=y2-y1/x2-xOr y-y1= m (x – x1)

The linear equation can also be written as,

ax + by + c = 0

where a,b and c are constants

Linear Graph Examples

Let us understand the Linear graph definition with examples.

  1. The equation y=2x+1 is a linear equation or forms a straight line on the graph. When the value of x increases, then ultimately the value of y also increases by twice of the value of x plus 1.
  2. Suppose, if we have to plot a graph of a linear equation y=2x+1.

Let us consider y=2x+1 forms a straight line. Now, first, we need to find the coordinates of x and y by constructing the below table;

x -2 -1 0 1 2

Now calculating value of y with respect to x, by using given linear equation,


y=2(-2)+1= -3 for x=-2

y=2(-1)+1= -1 for x=-1

y=2(0)+1= 1 for x=0

y=2(1)+1= 3 for x=1

y=2(2)+1= 5 forx=2

So the table can be re-written as;

x -2 -1 0 1 2
y -3 -1 1 3 5

Now based on these coordinates we can plot the graph as shown below.

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