Telescoping series are series in which all but the first and last terms cancel out. If you think about the way that a long telescope collapses on itself, you can better understand how the middle of a telescoping series cancels itself. To determine whether a series is telescoping, we’ll need to calculate at least the first few terms to see whether the middle terms start canceling with each other.
Read MoreWe can use the p-series test for convergence to say whether or not a_n will converge. The p-series test says that a_n will converge when p>1 but that a_n will diverge when p≤1. The key is to make sure that the given series matches the format above for a p-series, and then to look at the value of p to determine convergence.
Read MoreWhen the terms of a series decrease toward 0, we say that the series is converging. Otherwise, the series is diverging. The nth term test is inspired by this idea, and we can use it to show that a series is diverging. Ironically, even though the nth term test is one of the convergence tests that we learn when we study sequences and series, it can only test for divergence, it can never confirm convergence.
Read MoreThe ratio test for convergence lets us determine the convergence or divergence of a series a_n using a limit, L. Once we find a value for L, the ratio test tells us that the series converges absolutely if L<1, and diverges if L>1 or if L is infinite. The test is inconclusive if L=1. The ratio test is used most often when our series includes a factorial or something raised to the nth power.
Read MoreThe root test is used most often when the series includes something raised to the nth power.The convergence or divergence of the series depends on the value of L. The series converges absolutely if L<1, diverges if L>1 (or L is infinite), and the root test is inconclusive if L=1.
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