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Ch. 5 - Integrals
Hass - Thomas' Calculus 15th Edition
Hass15th EditionThomas' CalculusISBN: 9780137616077Non è quello che usi tu?Cambia libro di testo
Capitolo 5, Problema 5.PE.13

In Exercises 11–14, find the total area of the region between the graph of f and the x-axis.
ƒ(x) = 5 - 5x²/³, -1 ≤ x ≤ 8

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First, understand that the total area between the graph of the function and the x-axis means we need to find the integral of the absolute value of the function over the interval \(-1 \leq x \leq 8\). This is because areas below the x-axis contribute positively to the total area when taken as absolute values.
Next, identify where the function \(f(x) = 5 - 5x^{2/3}\) intersects the x-axis by solving \(f(x) = 0\). Set \(5 - 5x^{2/3} = 0\) and solve for \(x\) to find the points where the graph crosses the x-axis.
Once the zeros are found, split the integral into subintervals where the function is either positive or negative. For each subinterval, set up the definite integral of \(|f(x)|\) which will be either \(f(x)\) or \(-f(x)\) depending on the sign of \(f(x)\) in that interval.
Write the total area as the sum of the integrals over these subintervals: \(\text{Area} = \int_{a}^{b} |f(x)| \, dx = \sum \int_{x_i}^{x_{i+1}} |f(x)| \, dx\), where \(x_i\) are the zeros and the endpoints \(-1\) and \(8\).
Finally, compute each integral separately by integrating \(f(x)\) or \(-f(x)\) as appropriate, using the power rule for integration on \(x^{2/3}\), and then sum the absolute values of these integrals to get the total area.

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