LINEAR GRAPHS

Just for your info:

When the gradient (m) is given, and one of the points in which the line touches (x,y) is stated,

and the equation of the line is required, there is this formulae.

m = y - y1/ x - x1

where m = gradient, x1 and y1 being the coordinates of the point in which the line touches and x and y being x and y..

Geddit?

Eg: Find the eqn of the line which touches a point (3,2) and has a gradient of 3

Sub...

3 = y - 2/x - 3

3x - 9 = y - 2

y = 3x - 7

=)

Another eqn.

When two points in which the line touches are given, (x1,y1), (x2,y2) are given, and the equation of the line is required, there is this formulae.

y - y1/x - x1 = y2 - y1/x2 - x1

Where (x1,y1), (x2,y2) are the points, and x and y being x and y...

eg: Fing the eqn of the line which passes through the points (3,2) and (5,8)

sub...

y - 3/x - 2 = 8 - 2/5 - 3

y - 3/x - 2 = 3

y - 3 = 3x - 6

y = 3x + 3

:D

Hoped this helped =)

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