Example 4.15.  Show that  [Graphics:Images/ComplexGeometricSeriesMod_gr_176.gif]  converges.

Explore Solution 4.15.

Enter the formula for the terms in the series.

[Graphics:../Images/ComplexGeometricSeriesMod_gr_179.gif]


[Graphics:../Images/ComplexGeometricSeriesMod_gr_180.gif]

 

 

  Use d'Alembert's ratio test. First, find the ratio of consecutive terms.

[Graphics:../Images/ComplexGeometricSeriesMod_gr_181.gif]




[Graphics:../Images/ComplexGeometricSeriesMod_gr_182.gif]

 

 

 

Since L < 1, the series converges.   

We can use Mathematica to find the sum of series.

[Graphics:../Images/ComplexGeometricSeriesMod_gr_183.gif]


[Graphics:../Images/ComplexGeometricSeriesMod_gr_184.gif]

 

 

Use Mathematica to construct some of the partial sums of the infinite series.

[Graphics:../Images/ComplexGeometricSeriesMod_gr_185.gif]




[Graphics:../Images/ComplexGeometricSeriesMod_gr_186.gif]

 

 

 

Use Mathematica to plot some of the partial sums of the infinite series.

[Graphics:../Images/ComplexGeometricSeriesMod_gr_187.gif]




[Graphics:../Images/ComplexGeometricSeriesMod_gr_188.gif]

[Graphics:../Images/ComplexGeometricSeriesMod_gr_189.gif]

We see that the infinite series  [Graphics:../Images/ComplexGeometricSeriesMod_gr_190.gif]  converges and that its sum is  [Graphics:../Images/ComplexGeometricSeriesMod_gr_191.gif].  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(c) 2006 John H. Mathews, Russell W. Howell