We look in this section at how to calculate coordinates and plot straight line graphs.
We also look at the gradient and intercept of a straight line and the equation of a straight line.
The gradient of a line is a measure of its steepness. The intercept of a line is the value where the line crosses the yaxis.
The equation of a straight line is y = mx + c, where
m = gradient and c = intercept (where the line crosses the yaxis).
Draw the graph with equation y = 2x + 3.
x  –2  –1  0  1  2  3 
y  –1  1  3  5  7  9 
Calculate the gradient of each of the following lines:
(a) 
 

(b) 
 
(c) 
 
(d) 

Determine the equation of each of the following lines:
(a)  (b) 

Gradient =  =  1 
Gradient =  =  2 