(a) (only 4115 students) Prove that the function ƒ (x₁, x₂) = log (e™¹ + e²²) is convex on R².

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
Section: Chapter Questions
Problem 1RQ
icon
Related questions
Question
100%
### Problem Statement

**1. (a) (only 4115 students)** Prove that the function 

\[ f(x_1, x_2) = \log(e^{x_1} + e^{x_2}) \]

is convex on \(\mathbb{R}^2\).

### Explanation:

This problem asks students to prove the convexity of a specific function, \( f(x_1, x_2) \), on the two-dimensional real number space, denoted as \(\mathbb{R}^2\). The function is defined as the natural logarithm of the sum of two exponential functions, \( e^{x_1} \) and \( e^{x_2} \).

### Understanding Convexity:

A function \( f \) is convex on a set if, for any two points \( \mathbf{x}, \mathbf{y} \) in that set and for any \( \lambda \) satisfying \( 0 \leq \lambda \leq 1 \), the following inequality holds:

\[ f(\lambda \mathbf{x} + (1-\lambda) \mathbf{y}) \leq \lambda f(\mathbf{x}) + (1-\lambda) f(\mathbf{y}) \]

To prove convexity, one can utilize the second-order conditions, which involve ensuring that the Hessian matrix of the function is positive semi-definite at all points in the domain.

No graphs or diagrams are included in this problem.
Transcribed Image Text:### Problem Statement **1. (a) (only 4115 students)** Prove that the function \[ f(x_1, x_2) = \log(e^{x_1} + e^{x_2}) \] is convex on \(\mathbb{R}^2\). ### Explanation: This problem asks students to prove the convexity of a specific function, \( f(x_1, x_2) \), on the two-dimensional real number space, denoted as \(\mathbb{R}^2\). The function is defined as the natural logarithm of the sum of two exponential functions, \( e^{x_1} \) and \( e^{x_2} \). ### Understanding Convexity: A function \( f \) is convex on a set if, for any two points \( \mathbf{x}, \mathbf{y} \) in that set and for any \( \lambda \) satisfying \( 0 \leq \lambda \leq 1 \), the following inequality holds: \[ f(\lambda \mathbf{x} + (1-\lambda) \mathbf{y}) \leq \lambda f(\mathbf{x}) + (1-\lambda) f(\mathbf{y}) \] To prove convexity, one can utilize the second-order conditions, which involve ensuring that the Hessian matrix of the function is positive semi-definite at all points in the domain. No graphs or diagrams are included in this problem.
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 2 steps with 2 images

Blurred answer
Recommended textbooks for you
Advanced Engineering Mathematics
Advanced Engineering Mathematics
Advanced Math
ISBN:
9780470458365
Author:
Erwin Kreyszig
Publisher:
Wiley, John & Sons, Incorporated
Numerical Methods for Engineers
Numerical Methods for Engineers
Advanced Math
ISBN:
9780073397924
Author:
Steven C. Chapra Dr., Raymond P. Canale
Publisher:
McGraw-Hill Education
Introductory Mathematics for Engineering Applicat…
Introductory Mathematics for Engineering Applicat…
Advanced Math
ISBN:
9781118141809
Author:
Nathan Klingbeil
Publisher:
WILEY
Mathematics For Machine Technology
Mathematics For Machine Technology
Advanced Math
ISBN:
9781337798310
Author:
Peterson, John.
Publisher:
Cengage Learning,
Basic Technical Mathematics
Basic Technical Mathematics
Advanced Math
ISBN:
9780134437705
Author:
Washington
Publisher:
PEARSON
Topology
Topology
Advanced Math
ISBN:
9780134689517
Author:
Munkres, James R.
Publisher:
Pearson,