The Straight Line
A straight line is the shortest distance between
two points.
· The Gradient of a line is a measure of its slope
relative to the x axis.
A positive gradient goes upwards, from left to right.
A negative gradient goes downwards, from left to right.
The gradient is found by dividing the vertical distance by
the horizontal distance.
Examples
· A line can be drawn from its equation
The line y = x has values
|
Table of Values of Equation y = x |
|||||||||
|
x |
-4 |
-3 |
-2 |
-1 |
0 |
1 |
2 |
3 |
4 |
|
y |
-4 |
-3 |
-2 |
-1 |
0 |
1 |
2 |
3 |
4 |
Giving the co-ordinates
( -4, -4), (-3,-3) , ( -2, -2), (-1,-1), ( 0, 0), (1,1) ,(2,2), (3,3), (4,4)
These values are then plotted on a graph.
The line y = 2x has values
|
Table of Values of Equation y = 2x |
|||||||||
|
x |
-4 |
-3 |
-2 |
-1 |
0 |
1 |
2 |
3 |
4 |
|
y |
-8 |
-6 |
-4 |
-2 |
0 |
2 |
4 |
6 |
8 |
and graph
· The equation of a straight line is
y = mx + c
Where m= gradient and c = y-intercept,
the value of y when x is zero.
Plotting the graph of a line from its equation.
Finding the equation of a line from its graph.