STRAIGHT LINE GRAPHS y = mx + c.

Presentation on theme: "STRAIGHT LINE GRAPHS y = mx + c."— Presentation transcript:

STRAIGHT LINE GRAPHS y = mx + c

STRAIGHT LINE GRAPHS ALL are of the form y = mx +c
m is the GRADIENT of the line c is the ‘y intercept’

STRAIGHT LINE GRAPHS We must to be able to DRAW THE GRAPHS
FIND THE EQUATION FROM A GRAPH

STRAIGHT LINE GRAPHS DRAWING THE GRAPHS WE NEED TO IDENTIFY TWO POINTS
POINT 1 IS THE y INTERCEPT POINT 2 IS FOUND BY SUBSTITUTING A VALUE FOR x INTO THE FUNCTION DRAWING THE GRAPHS

If we use the example y = 3x - 1
STRAIGHT LINE GRAPHS If we use the example y = 3x - 1 The y intercept is -1 REMEMBER (y = mx + c) So point 1 is (0,-1) If we substitute x = 1 then y = 3 - 1 so y = 2 So point 2 is (1,2)

STRAIGHT LINE GRAPHS NOTE THE TWO POINTS CHOSEN
THE FINISHED GRAPH LOOKS LIKE THIS NOTE THE TWO POINTS CHOSEN

NOW WE MUST LEARN HOW TO FIND AN EQUATION FROM A GRAPH
STRAIGHT LINE GRAPHS NOW WE MUST LEARN HOW TO FIND AN EQUATION FROM A GRAPH

STRAIGHT LINE GRAPHS SO ‘C’ IS -4 IF WE USE THIS GRAPH
WE CAN SEE THAT THE LINE CROSSES THE Y AXIS AT THE POINT (0,-4) SO ‘C’ IS -4

STRAIGHT LINE GRAPHS The gradient (m) is defined as

STRAIGHT LINE GRAPHS We need to find m (the gradient)
We need to find the change in y We need to find the change in x The change in y is 4 The change in x is 2

STRAIGHT LINE GRAPHS So m = 2 Since the gradient is defined as

We know the equation of the line is
STRAIGHT LINE GRAPHS STRAIGHT LINE GRAPHS As y = mx + c We know the equation of the line is y = 2x - 4