The general equation of a line iswhere
and
are the variables that label the axes and m and c are constants.
-
is called the independent variable. It is the variable that can be controlled in an experiment.
-
is called the dependent variable. It changes in response to a change in
-
is the gradient, equal to a change in
along the graph divided by a change in
-
is the
intercept – the point on the
axis where the line crosses.
Often a direct plot of the variables will produce a straight line. If so then we can find the gradient and– intercept from the graph and use the resulting equation to find any value of
given a value of
and vice versa.
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The gradient of the graph above is approximately