Quod Erat Demonstrandum

2010/09/29

0 還是 1

Filed under: Fun,Junior Form Mathematics — johnmayhk @ 11:21 上午

一早知 EXCEL 是設計給 Office 用,非數學研究。那天計算

(1613673)^3 + (-2262756)^3 + (1947250)^3 = ?

答案竟然是 (more…)

2010/09/28

唔用 MI

Filed under: Pure Mathematics — johnmayhk @ 12:36 下午

以下例題在 mathematical induction 一課:

Prove that

1. Show that the product of 4 consecutive positive integers is divisible by 4!.

2. Show that 1 + \frac{1}{\sqrt{2}} + \frac{1}{\sqrt{3}} + \dots + \frac{1}{\sqrt{n}} > 2(\sqrt{n + 1} - 1) (\forall n \in \mathbb{N}).

但,它們不一定以 M.I.處理。 (more…)

2010/09/27

series by wolfram alpha

Filed under: Additional / Applied Mathematics,HKALE — johnmayhk @ 5:40 下午

早前和中七同學談 Series,因書中習題:

Expand \sin^{-1}x about x = 0.

沒有答案,我在

http://www.wolframalpha.com/

輸入 (more…)

2010/09/24

簡單的初中直線題目

Filed under: Junior Form Mathematics — johnmayhk @ 1:03 下午

這是中三的直線方程題目。

1. Given that A(4,-9), B(-4,-3), C(5,9), find the coordinates of the

(a) centroid(形心);
(b) orthocenter(垂心) and
(c) circumcenter(外心) of \Delta ABC.

(more…)

2010/09/23

唔打:基本功之節節相消

Filed under: Pure Mathematics — johnmayhk @ 3:23 下午

(more…)

2010/09/18

[Gag] fb

Filed under: Fun — johnmayhk @ 8:38 上午

雖然我非顏冊控,

但也不會仇facebook的, (more…)

2010/09/14

唔打:錯在哪裡之方程組

Filed under: Pure Mathematics — johnmayhk @ 8:59 下午

(more…)

2010/09/13

[學具][YouTube] MythBusters- Folding Paper Seven plus times

Filed under: Fun — johnmayhk @ 1:56 下午

不止紙上談兵,真的做出來。

2010/09/11

[學具] logic

Filed under: Fun — johnmayhk @ 10:08 下午

2010/09/03

因式分解 x^n – 1

Filed under: Pure Mathematics — johnmayhk @ 1:06 下午

中學時代的數學參考書 Methods of A-Level Pure Mathematics (Volume 1) 記載了以下問題。

觀察

x^2 - 1 \equiv (x - 1)(x + 1)
x^3 - 1 \equiv (x - 1)(x^2 + x + 1)
x^4 - 1 \equiv (x - 1)(x + 1)(x^2 + 1)
x^5 - 1 \equiv (x - 1)(x^4 + x^3 + x^2 + x + 1)
x^6 - 1 \equiv (x - 1)(x + 1)(x^2 - x + 1)(x^2 + x + 1)

\dots

1938 年,柴巴塔洛夫(Tschebotarev)猜想:對於任何正整數 n,x^n - 1 的因式(factor)不存在大於 1 或少於 -1 的係數(coefficients)。這個對嗎? (more…)

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