Find positive numbers a and b so that the change of variables s = ax, t = by transforms the integral S S dx dy into a = for the region R, the elliptical region x2²/25 + y²/16 ≤ 1 and the region T, the circle s² + t² = 1. b What is (x,y) a(s,t) Ə(x,y) a(s,t) = Ə(x, y) ||, ost) in this case? ds dt

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### Changing Variables in Double Integrals: An Example

**Problem Statement:**

Find positive numbers \(a\) and \(b\) so that the change of variables \(s = ax, t = by\) transforms the integral 

\[
\iint_{R} dx \, dy
\]

into 

\[
\iint_{T} \left|\frac{\partial(x,y)}{\partial(s,t)}\right| ds \, dt
\]

for the regions \(R\) and \(T\):

- The region \(R\) is the elliptical region defined by \(x^2/25 + y^2/16 \leq 1\).
- The region \(T\) is the circular region defined by \(s^2 + t^2 = 1\).

**To Do:**

1. Determine the values of \(a\) and \(b\).
2. Find the value of the Jacobian determinant \(\left|\frac{\partial(x,y)}{\partial(s,t)}\right|\) for this change of variables.

**Solution Steps:**

1. **Finding \(a\) and \(b\):**
   
   First, we need to transform the ellipse \(x^2/25 + y^2/16 = 1\) into a circle \(s^2 + t^2 = 1\).

   \[
   s = ax \implies a^2x^2
   \]
   \[
   t = by \implies b^2y^2
   \]

   So, we have:
   
   \[
   \frac{a^2 x^2}{25} + \frac{b^2 y^2}{16} = 1
   \]
   
   Since \(x=5\) and \(y=4\) are points on the ellipse that correspond to the points on the unit circle when scaled properly, we get:
   
   \[
   a = \frac{1}{5}
   \]
   \[
   b = \frac{1}{4}
   \]

2. **Finding the Jacobian determinant:**

   The Jacobian determinant \(\left|\frac{\partial(x,y)}{\partial(s,t)}\right|\) is calculated as:

   \[
   \frac{\partial(x,y)}{\partial(s,t)} = \begin{vmatrix}
    \
Transcribed Image Text:### Changing Variables in Double Integrals: An Example **Problem Statement:** Find positive numbers \(a\) and \(b\) so that the change of variables \(s = ax, t = by\) transforms the integral \[ \iint_{R} dx \, dy \] into \[ \iint_{T} \left|\frac{\partial(x,y)}{\partial(s,t)}\right| ds \, dt \] for the regions \(R\) and \(T\): - The region \(R\) is the elliptical region defined by \(x^2/25 + y^2/16 \leq 1\). - The region \(T\) is the circular region defined by \(s^2 + t^2 = 1\). **To Do:** 1. Determine the values of \(a\) and \(b\). 2. Find the value of the Jacobian determinant \(\left|\frac{\partial(x,y)}{\partial(s,t)}\right|\) for this change of variables. **Solution Steps:** 1. **Finding \(a\) and \(b\):** First, we need to transform the ellipse \(x^2/25 + y^2/16 = 1\) into a circle \(s^2 + t^2 = 1\). \[ s = ax \implies a^2x^2 \] \[ t = by \implies b^2y^2 \] So, we have: \[ \frac{a^2 x^2}{25} + \frac{b^2 y^2}{16} = 1 \] Since \(x=5\) and \(y=4\) are points on the ellipse that correspond to the points on the unit circle when scaled properly, we get: \[ a = \frac{1}{5} \] \[ b = \frac{1}{4} \] 2. **Finding the Jacobian determinant:** The Jacobian determinant \(\left|\frac{\partial(x,y)}{\partial(s,t)}\right|\) is calculated as: \[ \frac{\partial(x,y)}{\partial(s,t)} = \begin{vmatrix} \
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