# Quod Erat Demonstrandum

## 2017/04/22

### 逆矩陣

Filed under: mathematics,NSS,University Mathematics — johnmayhk @ 11:10 下午
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$AB=BA=I$

## 2017/04/21

### 三垂線定理

Filed under: mathematics,NSS,Pure Mathematics,University Mathematics — johnmayhk @ 12:56 下午
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（一）前言

## 2016/07/22

### 有理函數和矩陣

Filed under: NSS,Pure Mathematics,Teaching,University Mathematics — johnmayhk @ 12:06 下午
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Core mathematics 介紹過 rational function（有理函數），即形如　$\frac{P(x)}{Q(x)}$　者（其中 $P(x)$$Q(x)$ 皆為多項式）。

$P(x)$$Q(x)$ 皆為線性（linear），即形如　$\frac{ax+b}{cx+d}$　者，稱之曰 fractional linear function（FLF）。

$f(f(x))$

$=\frac{af(x)+b}{cf(x)+d}$

$=\frac{a\times \frac{ax+b}{cx+d}+b}{c\times \frac{ax+b}{cx+d}+d}$

$=\frac{(a^2+bc)x+b(a+d)}{c(a+d)x+bc+d^2}$

## 2015/09/22

### 質數定理

Filed under: Pure Mathematics,University Mathematics — johnmayhk @ 3:37 下午
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http://www.mathdb.org/articles/prime/c_prime.htm

## 2013/03/27

### fs gif

Filed under: University Mathematics — johnmayhk @ 3:34 下午

## 2013/02/04

### 中大數訊

Filed under: Report,University Mathematics — johnmayhk @ 9:08 上午

More at (more…)

## 2013/01/05

### CT

Filed under: University Mathematics — johnmayhk @ 9:00 上午

Introduction to Category Theory 1: Course Overview

## 2012/10/31

### [FW] Mathematical Physics – Carl Bender

Filed under: University Mathematics — johnmayhk @ 2:38 下午

02 (more…)

## 2012/09/12

### abc 猜想

Filed under: Report,University Mathematics — johnmayhk @ 11:55 上午

[News] Proof claimed for deep connection between primes
http://www.nature.com/news/proof-claimed-for-deep-connection-between-primes-1.11378

[Wiki] abc conjecture
http://en.wikipedia.org/wiki/Abc_conjecture

[Mathoverflow] Philosophy behind Mochizuki’s work on the ABC conjecture
http://mathoverflow.net/questions/106560/philosophy-behind-mochizukis-work-on-the-abc-conjecture

## 2012/09/05

### [FW] 邵逸夫奬2012第2集數學科學獎

Filed under: Report,University Mathematics — johnmayhk @ 4:59 下午

## 2012/08/28

### 幾個可能用得著的拓樸片子

Filed under: Fun,University Mathematics — johnmayhk @ 2:08 下午

1.

2.

## 2012/01/18

### [News] BSD猜想有望破解 華數學家轟動學界

Filed under: Report,University Mathematics — johnmayhk @ 11:06 上午

BSD猜想有望破解 華數學家轟動學界 (more…)

## 2011/03/30

### [FW][TED]Marcus du Sautoy: Symmetry, reality’s riddle

Filed under: Fun,University Mathematics — johnmayhk @ 5:41 上午

## 2011/03/08

Filed under: Physics,University Mathematics — johnmayhk @ 5:27 下午

## 2010/11/17

### 證明 Euler’s formula

Filed under: Junior Form Mathematics,University Mathematics — johnmayhk @ 3:10 下午

$V - E + F = 2$

http://www.ics.uci.edu/~eppstein/junkyard/euler/