How do you use integration to find the area bounded …

Mathematics Questions

How do you use integration to find the area bounded by the ellipse (9x^2 + 25y^2 = 225), the lines (x = -2) and (x = 2), and the x-axis?

Short Answer

To calculate the area bounded by the ellipse defined by 9x¬¨‚â§ + 25y¬¨‚â§ = 225 and the x-axis, we first rearranged the equation to x¬¨‚â§/25 + y¬¨‚â§/9 = 1. We set up the integral to find the area above the x-axis from x = -2 to x = 2, which we solved to find the area is (5 – ‚Äöao21) square units.

Step-by-Step Solution

Step 1: Rearranging the Ellipse Equation

To begin calculating the area bounded by the ellipse and the given lines, we first need to rearrange the equation of the ellipse (9x² + 25y² = 225). This can be simplified by dividing every term by 225, resulting in the equation (x²/25 + y²/9 = 1). This representation indicates that we have an ellipse centered at the origin with its major axis along the y-axis, as the larger denominator corresponds to the y² term.

Step 2: Setting Up the Integral

Next, we will set up the integral to calculate the area between the ellipse and the x-axis from (x = -2 to x = 2). The upper half of the ellipse can be represented mathematically as (y = (3/5)‚Äöao(225 – 9x¬¨‚â§)). We will integrate this function to cover the range of x-values, and to find the total area, we will use the integral:

  • A = 2 ‚Äöa¬¥(from 0 to 2) (3/5)‚Äöao(225 – 9x¬¨‚â§) dx

Step 3: Solving the Integral

Finally, we will solve the integral using the substitution method. By letting (u = 225 – 9x¬¨‚â§), we derive the new limits of integration and change the differential. The integral transforms, allowing us to evaluate it effectively. Ultimately, we find the area bounded by the ellipse and the specified lines to be (5 – ‚Äöao21) square units, concluding the calculation.

Related Concepts

Ellipse Equation

A mathematical representation of an ellipse, typically in the standard form (x²/a² + y²/b² = 1), which defines its shape and orientation in the cartesian plane.

Integral

A fundamental concept in calculus that represents the area under a curve, calculated using limits of integration to sum infinitesimal quantities over a specified range.

Substitution Method

A technique used in integration where a new variable is introduced to simplify the integral, allowing for easier evaluation of the integral through transformations of the function and its limits.

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