Skip to main content
Ch. 7 - Transcendental Functions
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Non è quello che usi tu?Cambia libro di testo
Capitolo 7, Problema 7.AAE.7a

7. Let A(t) be the area of the region in the first quadrant enclosed by the coordinate axes, the curve y=e^(-x), and the vertical line x=t, t>0. Let V(t) be the volume of the solid generated by revolving the region about the x-axis. Find the following limits.
a. lim(x→∞)A(t)

Guida verificata passo dopo passo
1
First, understand the region described: it is bounded by the x-axis (y=0), the y-axis (x=0), the curve \(y = e^{-x}\), and the vertical line \(x = t\) where \(t > 0\).
To find the area \(A(t)\) of this region, set up the definite integral of the function \(y = e^{-x}\) from \(x=0\) to \(x=t\): \[A(t) = \int_0^t e^{-x} \, dx\]
Evaluate the integral symbolically (do not compute the final value yet): \[\int e^{-x} \, dx = -e^{-x} + C\] So, \[A(t) = [-e^{-x}]_0^t = (-e^{-t}) - (-e^{0}) = 1 - e^{-t}\]
Now, to find the limit as \(t\) approaches infinity, consider the behavior of \(e^{-t}\) as \(t \to \infty\). Since \(e^{-t}\) approaches 0, the expression \(1 - e^{-t}\) approaches 1.
Therefore, the limit is \[\lim_{t \to \infty} A(t) = 1\] This represents the total area under the curve \(y = e^{-x}\) from 0 to infinity in the first quadrant.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
3m

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Definite Integral as Area Under a Curve

The area A(t) under the curve y = e^(-x) from x = 0 to x = t is found using a definite integral. This integral sums the infinitesimal areas of vertical slices, representing the total area enclosed by the curve, axes, and vertical line at x = t.
Video consigliato:
Percorso guidato
05:43
Definition of the Definite Integral

Limit of a Function as t Approaches Infinity

Evaluating lim(t→∞) A(t) involves understanding the behavior of the integral as the upper limit grows without bound. This often requires recognizing improper integrals and determining if the area converges to a finite value or diverges.
Video consigliato:
06:11
Limits of Rational Functions: Denominator = 0

Exponential Decay Function

The function y = e^(-x) is an exponential decay curve that approaches zero as x increases. Its properties ensure the area under the curve from 0 to infinity converges, which is key to finding the limit of A(t) as t approaches infinity.
Video consigliato:
09:29
Exponential Growth & Decay