In this activity, we will use straight line graphs in the form y = mx + c. We will be able to see if a given coordinate lies on the lines given.
For a straight line graph we use the form:
y = mx + c
m is the gradient
c is the y intercept
Let's have a look at a typical question!
Does the point P (2, 4) lie on the straight line y = 3x - 2?
The point P (2, 4) means when x = 2, y = 4
If it lies on the line y = 3x - 2 then we can substitute these values in and the equation should be true!
If not, then the point cannot lie on the line!
We have y = 3x - 2
Let's put our x and y values in there from point P:
y = 4 and x = 2
4 = (3x2) - 2
4 = 6 - 2
4 = 4 it's correct!
Therefore, the point P does lie on the line y = 3x - 2
If this had not been correct, then the point P would not lie on the line!
Let's try some questions.