Confirm that the Integral Test can be applied to the series. Then use the Integral Test to determine the convergence or divergence of the series. sum_{n=1}^infty3^{-n}

shadsiei

shadsiei

Answered question

2021-01-05

Confirm that the Integral Test can be applied to the series. Then use the Integral Test to determine the convergence or divergence of the series.
n=13n

Answer & Explanation

diskusje5

diskusje5

Skilled2021-01-06Added 82 answers

Integral test:
If f(x) is continuous, positive and decreasing function on [k,] and f(n)=an then
If kf(x)dx is convergent then n=kan is also convergent.
If kf(x)dx is divergent then n=kan is also divergent.
Given that
n=13n
Here an=3n
Since an=3n so functon f(x) is
f(x)=3x
F(x) is positive and decreasing so integral test is applicable for the given series.
Now evaluate kf(x)dx so
13xdx=[3xln3]1
=3ln3+31ln3
=0+13ln3
=13ln3
Since 13xdx is convergent. Hence using integral test n=13n is also convergent.

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