Chapter 5: straight line graphs

Y intercept form of the equation of a line

y=mx +c

Equation of a line’standard form’

ax+by+c=0

What can we do when we have a point(or two) that lies on a line

We can substitute the values of a coordinate into the equation

Gradient

‘ m’ change in y/ change in x

• shows us what y changes by as x increases. Y 1

A level , easier equation of a line

y-y1=m(x-x1)

Gradient of a perpendicular line

the negative reciprocal of the gradient of the original line

Parallel lines

they have the same gradient and never intersect

How do we find the points where two lines intersect

solve the equations of the lines simultaneously(we find x and y)

How do we find the distance between two points

pythagoras’ theorem (change in y + change in x -it’s squared rooted)

Main points for modelling with linear equations

-relate to real life example

-try not to leave answer in fraction

-prediction outside data= extrapolation