Jacobian Determinant 9622D9
1. **State the problem:** Find the Jacobian determinant $\frac{\partial(u,v,w)}{\partial(x,y,z)}$ where
$$u = x^2 - 2y, \quad v = x + y + z, \quad w = x - 2y + 3.$$
2. **Recall the formula for the Jacobian:**
The Jacobian matrix $J$ is given by
$$J = \begin{bmatrix}
\frac{\partial u}{\partial x} & \frac{\partial u}{\partial y} & \frac{\partial u}{\partial z} \\
\frac{\partial v}{\partial x} & \frac{\partial v}{\partial y} & \frac{\partial v}{\partial z} \\
\frac{\partial w}{\partial x} & \frac{\partial w}{\partial y} & \frac{\partial w}{\partial z}
\end{bmatrix}$$
The Jacobian determinant is $\det(J)$.
3. **Calculate each partial derivative:**
- For $u = x^2 - 2y$:
- $\frac{\partial u}{\partial x} = 2x$
- $\frac{\partial u}{\partial y} = -2$
- $\frac{\partial u}{\partial z} = 0$
- For $v = x + y + z$:
- $\frac{\partial v}{\partial x} = 1$
- $\frac{\partial v}{\partial y} = 1$
- $\frac{\partial v}{\partial z} = 1$
- For $w = x - 2y + 3$:
- $\frac{\partial w}{\partial x} = 1$
- $\frac{\partial w}{\partial y} = -2$
- $\frac{\partial w}{\partial z} = 0$
4. **Form the Jacobian matrix:**
$$J = \begin{bmatrix}
2x & -2 & 0 \\
1 & 1 & 1 \\
1 & -2 & 0
\end{bmatrix}$$
5. **Calculate the determinant:**
$$\det(J) = 2x \begin{vmatrix}1 & 1 \\ -2 & 0\end{vmatrix} - (-2) \begin{vmatrix}1 & 1 \\ 1 & 0\end{vmatrix} + 0 \begin{vmatrix}1 & 1 \\ 1 & -2\end{vmatrix}$$
Calculate each minor:
- $\begin{vmatrix}1 & 1 \\ -2 & 0\end{vmatrix} = (1)(0) - (1)(-2) = 0 + 2 = 2$
- $\begin{vmatrix}1 & 1 \\ 1 & 0\end{vmatrix} = (1)(0) - (1)(1) = 0 - 1 = -1$
- The last term is multiplied by zero, so it is zero.
6. **Substitute back:**
$$\det(J) = 2x \cdot 2 - (-2) \cdot (-1) + 0 = 4x - 2$$
7. **Final answer:**
$$\boxed{\det\left(\frac{\partial(u,v,w)}{\partial(x,y,z)}\right) = 4x - 2}$$
This is the Jacobian determinant of the transformation.