Reciprocal of a Function

The following guidelines are useful in order to sketch the reciprocal of a function given the graph of the original function:
Where

is positive or negative then

is also positive or negative respectively.
Where

has zero(s) then the reciprocal function

has vertical asymptote(s) and vice versa.
Where

has a horizontal asymptote at y=c then the reciprocal function

has also horizontal asymptote at

.
Where the original function

is increasing then the reciprocal function

is decreasing.
Where the original function

is decreasing then the reciprocal function

is increasing.
If the original function

has a maximum at

then the reciprocal function

has a minimum at

.
If the original function

has a minimum at

then the reciprocal function

has a maximum at

.
If the original function

has a point of inflexion at

then the reciprocal function

has also a point of inflexion at

.