Grade 12 · Algebra & functions

Convergence tests practice

Convergence tests is a grade 12 math skill: apply convergence tests (ratio, comparison, alternating series) to determine whether an infinite series converges. Below are 3 practice questions with answers and step-by-step explanations, drawn from the 5 convergence tests problems our math games drill.

5 questions in the bank
Sample questions

Try 3 for free

Question 1easy

The harmonic series 1n\displaystyle\sum \dfrac{1}{n} is:

The harmonic series is a p-series with p=1p = 1. Since p1p \le 1, it diverges.

Question 2easy

Which test is best for n!nn\displaystyle\sum \dfrac{n!}{n^n}?

Factorials in the numerator make the Ratio test the natural choice.

Question 3easy

Which test should you try first for 1n2n\displaystyle\sum \dfrac{1}{n \cdot 2^n}?

The 2n2^n in the denominator makes the Ratio test efficient: an+1an12<1\dfrac{a_{n+1}}{a_n} \to \dfrac{1}{2} < 1.

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