Curve Sketching
 

 

 

Contents

 

Curve Sketching

 

Techniques

 

Quadratic Functions

 

Higher Degree Equations

 

Rectangular Hyperbolas

 

Conic Sections

 

Modulus Functions

 

Rational Functions

 

Geometry Main Page 

Rectangular Hyperbolas
 
 

When the function is in the form 1/xn, the graph is a rectangular hyperbola. There are two types:

When n = 2k + 1, ie. n is an odd integer

                         

                                                     

When n = 2k, ie. n is an even integer

                        

                                                   

 
Properties of the rectangular hyperbola:
1. There is a vertical asymptote at x = 0.
2. There is a horizontal asymptote at y = 0.
3. There are no stationary points.
4. There are no intercepts (since the axes are asymptotes. This is NOT TRUE when the axes are not asymptotes.)
5. For n = odd integer, the gradient is always decreasing throughout the defined portion of x.
6. For n = even integer, the gradient when x < 0 is always increasing, whilst the gradient when x > 0 is always decreasing.
 
Example: Sketch the graph of
                               
 
Solution:
 
1. Intercepts: when x = 0, y = -1
                when y = 0, x = 1
 
2. Turning point:
       There are no turning points for this kind of graph.
 
3. Asymptotes:
         As x tends to infinity, y tends to 1.
         As y tends to infinity, x tends to -1.
     x = -1 is a vertical asymptote and y = 1 is a horizontal asymptote.
 
4. Gradient:
         dy/dx is always positive.
         The gradient is always increasing.