And Justify True OR False f(a, b) = (a-2)² + (6-3)³. Then, we say Pornt (2.31 T f=R²-)R. is local min of f over R²

Advanced Engineering Mathematics
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ISBN:9780470458365
Author:Erwin Kreyszig
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Chapter2: Second-order Linear Odes
Section: Chapter Questions
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### True or False and Justify

Consider the function \( f(a, b) = (a - 2)^2 + (b - 3)^3 \), where \( f: \mathbb{R}^2 \rightarrow \mathbb{R} \).

We need to determine if the statement "The point \((2, 3)^T\) is a local minimum of the function \( f \) over \(\mathbb{R}^2\)" is true or false.

#### Analysis

The given function is:

\[ f(a, b) = (a - 2)^2 + (b - 3)^3 \]

To analyze if the point \((2, 3)^T\) is a local minimum, let's consider the nature of the function and the behavior of each term:

1. The term \((a - 2)^2\) is always non-negative and equals zero when \(a = 2\).
2. The term \((b - 3)^3\) changes sign as \(b\) crosses 3 and has a critical point at \(b = 3\), where its value is also zero.

In order to have a local minimum at \((2, 3)\), both the first and second partial derivatives of \(f\) need to satisfy certain conditions. Specifically, the gradient \( \nabla f \) should be zero at \((2, 3)\) and the Hessian matrix should be positive definite.

#### Gradient Calculation

Calculate the partial derivatives:

\[
\frac{\partial f}{\partial a} = 2(a - 2)
\]

\[
\frac{\partial f}{\partial b} = 3(b - 3)^2
\]

Evaluating at \((a, b) = (2, 3)\):

\[
\frac{\partial f}{\partial a}\bigg|_{(2, 3)} = 2(2 - 2) = 0
\]

\[
\frac{\partial f}{\partial b}\bigg|_{(2, 3)} = 3(3 - 3)^2 = 0
\]

Therefore, \( \nabla f(2, 3) = (0, 0) \), so the gradient condition is satisfied.

#### Hessian Matrix Calculation

Calculate the second partial derivatives to form
Transcribed Image Text:### True or False and Justify Consider the function \( f(a, b) = (a - 2)^2 + (b - 3)^3 \), where \( f: \mathbb{R}^2 \rightarrow \mathbb{R} \). We need to determine if the statement "The point \((2, 3)^T\) is a local minimum of the function \( f \) over \(\mathbb{R}^2\)" is true or false. #### Analysis The given function is: \[ f(a, b) = (a - 2)^2 + (b - 3)^3 \] To analyze if the point \((2, 3)^T\) is a local minimum, let's consider the nature of the function and the behavior of each term: 1. The term \((a - 2)^2\) is always non-negative and equals zero when \(a = 2\). 2. The term \((b - 3)^3\) changes sign as \(b\) crosses 3 and has a critical point at \(b = 3\), where its value is also zero. In order to have a local minimum at \((2, 3)\), both the first and second partial derivatives of \(f\) need to satisfy certain conditions. Specifically, the gradient \( \nabla f \) should be zero at \((2, 3)\) and the Hessian matrix should be positive definite. #### Gradient Calculation Calculate the partial derivatives: \[ \frac{\partial f}{\partial a} = 2(a - 2) \] \[ \frac{\partial f}{\partial b} = 3(b - 3)^2 \] Evaluating at \((a, b) = (2, 3)\): \[ \frac{\partial f}{\partial a}\bigg|_{(2, 3)} = 2(2 - 2) = 0 \] \[ \frac{\partial f}{\partial b}\bigg|_{(2, 3)} = 3(3 - 3)^2 = 0 \] Therefore, \( \nabla f(2, 3) = (0, 0) \), so the gradient condition is satisfied. #### Hessian Matrix Calculation Calculate the second partial derivatives to form
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