3.11
Indeterminate forms can arise in limits of products, where one factor approaches zero, and the other tends to plus or minus infinity.
The result is indeterminate or unclear. It could be zero, infinite, or a finite number.
For example, consider the one-sided limit of the following product function.
As x tends to zero, the first factor x decreases to zero, while the second factor, the natural log of one over x, tends to infinity.
The product is algebraically equal to a quotient that can be written in two different expressions.
The first expression creates an infinity over infinity form, while the second expression creates a zero over zero form.
L’Hôpital’s Rule can be applied to either form. But, using the first form simplifies the differentiation and gives zero as a result.
A helpful visualization is a regular polygon inscribed in a circle. As the number of sides increases infinitely, each side shrinks toward zero.
This creates an indeterminate product: infinite sides times zero length. Yet, the total perimeter approaches the circle’s fixed circumference.
This shows how a zero-times-infinity form can produce a meaningful, finite result.
Indeterminate forms also arise in the evaluation of limits involving products, particularly when one factor approaches zero while the other tends to p…
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