109_sp2011_ho_injsurj_sol

# 109_sp2011_ho_injsurj_sol - 109 Spring 2011 Injections and...

This preview shows pages 1–2. Sign up to view the full content.

109 Spring 2011 - Injections and Surjections Exercise (II.12) . Suppose that A Z . Write the following statement entirely in symbols using the quantifiers and . Write out the negative of this statement in symbols. There is a greatest number in the set A . Give an example of a set A for which this statement is true. Give an example of a set A for which it is false. a A x A ( x a ) If A = { 1 , 2 , 5 } then the statement is true. If A = Z then the statement is false. Exercise (II.17) . Functions f : R R and g : R R are defined as follows. f ( x ) = x + 2 if x < 1, x if 1 x 1 x 2 if x > 1; g ( x ) = x 2 if x < 1, x if 1 x 1 x + 2 if x > 1 Find the functions f g , g f . Is g the inverse of f ? Is f injective or surjective? Is g ? f g ( x ) = x ; g f ( x ) = x if x < 3, ( x + 2) if 3 x < 1 x if 1 x 1 ( x 2) if 1 < x 3 x if x > 3 Since g f is not the identity map, g

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern