Area functions The graph of ƒ is shown in the figure. Let A(x) = ∫₋₂ˣ ƒ(t) dt and F(x) = ∫₄ˣ ƒ(t) dt be two area functions for ƒ. Evaluate the following area functions.
(d) F(4)

Verified step by step guidance

1. Step 1: Understand the problem. We are tasked with evaluating F(4), where F(x) = ∫₄ˣ ƒ(t) dt. This represents the net area under the curve of ƒ(t) from t = 4 to t = x. Specifically, F(4) means evaluating the integral from t = 4 to t = 4.
2. Step 2: Recall a key property of definite integrals. When the upper and lower limits of integration are the same, the integral evaluates to 0. Mathematically, ∫ₐₐ ƒ(t) dt = 0 for any function ƒ(t).
3. Step 3: Apply this property to the given integral. Since F(4) = ∫₄⁴ ƒ(t) dt, the integral evaluates to 0 because the interval of integration has no width.
4. Step 4: Confirm the reasoning using the graph. The graph shows areas labeled for different intervals, but since the interval from t = 4 to t = 4 has no length, no area is enclosed.
5. Step 5: Conclude that F(4) = 0 based on the mathematical property of definite integrals and the interpretation of the graph.

Key Concepts

Definite Integral

A definite integral represents the signed area under a curve between two points on the x-axis. It is calculated using the Fundamental Theorem of Calculus, which connects differentiation and integration. In this context, the area functions A(x) and F(x) are defined as definite integrals, allowing us to evaluate the total area under the curve of the function f(t) from a specified lower limit to an upper limit.

Area Function

An area function, such as A(x) or F(x), is a function that gives the accumulated area under a curve from a specific starting point to a variable endpoint x. For example, A(x) = ∫₋₂ˣ f(t) dt calculates the area from -2 to x, while F(x) = ∫₄ˣ f(t) dt calculates the area from 4 to x. These functions help in understanding how the area changes as x varies.

Evaluating Area Functions

To evaluate an area function at a specific point, such as F(4), one must compute the definite integral from the lower limit to the specified upper limit. In this case, F(4) = ∫₄⁴ f(t) dt, which represents the area under the curve from 4 to 4. Since the limits are the same, the result is zero, indicating no area is accumulated over that interval.