Mammoth Memory

Plotting lines on graph paper

Example 1

Plot the graph of y=x

This actually means y=mx+c

                                    y=1x+zero

Graph of y=x

First lets calculate some points on the graph.

x=-2      then   y=-2

x=-1      then   y=-1

x=0           then    y=0

x=1           then   y=1

x=2           then   y=2

 

Now draw a graph and mark on the above points

Mark the points on a graph

Now draw a straight line through these points

Connect the positions up y=x

 

Example 2

Plot the graph of  y+x=5

Always put the formula in the form  y=mx+c

                                                                 y=-1x+5

First lets calculate some points on the graph.

x=-2    then y=-1(-2)+5=7

x=-1    then y=-1(-1)+5=6

x=0         then y=-1(0)+5=5

x=1         then y=-1(1)+5=4

x=2        then y=-1(2)+5=3

 

Now draw a graph and mark on the above points

Mark the points on a graph

Now draw a straight line through these points

 Find the gradient of the resulting line

Example 3

Plot the graph of   2y-3x=7

Always put the formula in the form    y=mx+c

                                                                  2y=3x+7

                                                                  y=32x+72

                                                                  y=112x+312

First lets calculate some points on the graph.

x=-2   then y=1.5(-2)+3.5=0.5

x=-1   then y=1.5(-1)+3.5=2

x=0         then y=1.5(0)+3.5=3.5

x=1         then y=1.5(1)+3.5=5

x=2        then y=1.5(2)+3.5=6.5

 

Now draw a graph and mark on the above points

Mark the points on a graph

Now draw a straight line through these points

Find the gradient of the line but be careful, they are not all whole numbers