(5) Let ƒ : A → B and g : B → C, where f and g are functions and A, B, and C are sets. (a) Prove that if go f : A → C is invertible then g must be surjective and f must be in- jective. (b) Find functions f and g and sets A, B, and C which demonstrated gof can be invert- ible, even if g is not injective and f is not surjective.

Calculus: Early Transcendentals
8th Edition
ISBN:9781285741550
Author:James Stewart
Publisher:James Stewart
Chapter1: Functions And Models
Section: Chapter Questions
Problem 1RCC: (a) What is a function? What are its domain and range? (b) What is the graph of a function? (c) How...
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(5) Let f : A→ B and g : B → C, where f and g are functions and A, B, and C are sets.
(a) Prove that if gof : A → C is invertible then g must be surjective and f must be in-
jective.
(b) Find functions f and g and sets A, B, and C which demonstrated gof can be invert-
ible, even if g is not injective and f is not surjective.
Transcribed Image Text:(5) Let f : A→ B and g : B → C, where f and g are functions and A, B, and C are sets. (a) Prove that if gof : A → C is invertible then g must be surjective and f must be in- jective. (b) Find functions f and g and sets A, B, and C which demonstrated gof can be invert- ible, even if g is not injective and f is not surjective.
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