(a) Prove that, if f,g: R → R are convex functions and t≥ 0, then the function h(x) f(x) + tg(x) is convex. =

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

Mathematics - Optimization 

Please see image

 

(a) Prove that, if f,g: R → R are convex functions and t≥ 0, then the function h(x)
f(x) + tg(x) is convex.
=
(b) For which triples (a, b, c) of real numbers is the function f(x) = ax² + bx+c convex? Prove
your answer without using any calculus.
(c) For which integers n ≥ 1 is the function f(x) = = xn convex? You may use the fact that a
function f: R→ R such that f"(x) ≥ 0 for all x is convex, but not the converse of this fact.
(d) Is it true that the product of two convex functions f, g: R → R is always convex? Prove or
give a counterexample.
(e) Bonus: Give an example of a function f : R → R such that ƒ(1x1 + x₂) ≤ ½⁄ƒ(x1) + ½ ƒ (x2)
for all x1, x2 € R, but f is not convex. (Hint: this is a very very weird function. The fact
that R is a vector space over Q is relevant to its construction.).
Transcribed Image Text:(a) Prove that, if f,g: R → R are convex functions and t≥ 0, then the function h(x) f(x) + tg(x) is convex. = (b) For which triples (a, b, c) of real numbers is the function f(x) = ax² + bx+c convex? Prove your answer without using any calculus. (c) For which integers n ≥ 1 is the function f(x) = = xn convex? You may use the fact that a function f: R→ R such that f"(x) ≥ 0 for all x is convex, but not the converse of this fact. (d) Is it true that the product of two convex functions f, g: R → R is always convex? Prove or give a counterexample. (e) Bonus: Give an example of a function f : R → R such that ƒ(1x1 + x₂) ≤ ½⁄ƒ(x1) + ½ ƒ (x2) for all x1, x2 € R, but f is not convex. (Hint: this is a very very weird function. The fact that R is a vector space over Q is relevant to its construction.).
Expert Solution
steps

Step by step

Solved in 2 steps

Blurred answer
Similar questions
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,