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Is the power series ∑ [infinity]ₙ₌₁ (0.1)ⁿxⁿ convergent? If so, what is the radius of convergence?

asked
User Turix
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1 Answer

3 votes

Final answer:

The power series converges and has a radius of convergence of 10, determined by using the ratio test.

Step-by-step explanation:

The power series ∑ [infinity]ₙₜ₁ (0.1)^ₙx^ₙ is examined for convergence using the ratio test. We consider the absolute value of the ratio of the n+1 term to the n term:

|a_(n+1) / a_n| = |(0.1)^(n+1)x^(n+1) / (0.1)^ₙx^ₙ| = 0.1|x|

The series converges if this ratio is less than 1, hence it converges for |0.1x| < 1. This simplifies to |x| < 10, which means that the radius of convergence is 10.

answered
User Thedan
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8.5k points
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