Example 4.15. Show
that
converges.
Explore Solution 4.15.
Enter the formula for the terms in the series.
![]()
Use d'Alembert's ratio test. First, find the ratio of consecutive terms.
![[Graphics:../Images/ComplexGeometricSeriesMod_gr_182.gif]](../Images/ComplexGeometricSeriesMod_gr_182.gif)
Since L < 1, the series converges.
We can use Mathematica to find the sum of series.
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Use Mathematica to construct some of the partial sums of the infinite series.
![[Graphics:../Images/ComplexGeometricSeriesMod_gr_186.gif]](../Images/ComplexGeometricSeriesMod_gr_186.gif)
Use Mathematica to plot some of the partial sums of the infinite series.
![[Graphics:../Images/ComplexGeometricSeriesMod_gr_188.gif]](../Images/ComplexGeometricSeriesMod_gr_188.gif)
![[Graphics:../Images/ComplexGeometricSeriesMod_gr_189.gif]](../Images/ComplexGeometricSeriesMod_gr_189.gif)
We see that the infinite series
converges
and that its sum is
.