Multiplying By Negative Numbers Flips The Inequality Symbol (Proof)
Channel: Amour Learning
Date: 18/03/2021

My name is Kody Amour, and I make math videos for undergraduate math courses.

The textbook used in this video can be found here: https://www.jirka.org/ra/realanal.pdf
Credit to Dr. Jirí Lebl, who authored Basic Analysis I, which is a free open-source introduction to Real Analysis. This video is licensed under Creative Commons License.

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Support Amour Learning on Patreon: https://www.patreon.com/amourlearning
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Credit to all of the authors of all of the resources below that greatly helped influence this video.
Free open-access online math textbooks:
https://aimath.org/textbooks/approved-textbooks/

My favorite number theory textbooks:
Number Theory: In Context and Interactive by Dr. Karl-Dieter Crisman: http://math.gordon.edu/ntic/
Elementary Number Theory:
Primes, Congruences, and Secrets by Dr. William Stein: https://wstein.org/ent/
A Computational Introduction to Number Theory and Algebra by Dr. Victor Shoup: https://shoup.net/ntb/

My favorite programming language:
SageMath (which in my view is categorically better than Python, R, Mathematica, Matlab, Maple, Magma, etc - if you're using any of these and they aren't working out, switch to Sage): https://www.sagemath.org/

A free in-depth tutorial for SageMath: https://doc.sagemath.org/html/en/tutorial/

Learn LaTeX in 30 minutes: https://www.overleaf.com/learn/latex/Learn_LaTeX_in_30_minutes
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My favorite math-oriented YouTube channels (in no particular order):
Zach Star: https://www.youtube.com/channel/UCpCSAcbqs-sjEVfk_hMfY9w
Numberphile: https://www.youtube.com/channel/UCoxcjq-8xIDTYp3uz647V5A
3Blue1Brown: https://www.youtube.com/channel/UCYO_jab_esuFRV4b17AJtAw
MIT OpenCourseWare: https://www.youtube.com/channel/UCEBb1b_L6zDS3xTUrIALZOw
Khan Academy: https://www.youtube.com/channel/UC4a-Gbdw7vOaccHmFo40b9g
PBS Infinite Series: https://www.youtube.com/channel/UCs4aHmggTfFrpkPcWSaBN9g
Lex Fridman: https://www.youtube.com/user/lexfridman