グローバルビジネスで役立つ数学（74）中学生の気分で因数分解（英語版）

Hi there!

――If the outgoing words are beautiful, then the incoming words will be beautiful, too.

Still fresh in my memory that I quoted somewhere in my blog. I still never forget this quotation because it is simple, elegant, and impeccable.

In my early twenties, I visited Trinidad Tobago, an island country in the southeastern West Indies, before going to Curaçao in the southern Carrebian sea. If I remember correctly, it was at midnight past two to three o’clock when I was about to get my belongings inspected in the baggage claim of Piarco International Airport.

I had a lot of samples for sales promotions on overseas negotiations. The immigration staff lost no time fumbling inside my baggage, which made me nerve-wracked, and inadvertently, I used abusive language.

――What the hell are you doing!? Do you carry a grudge against the Japanese?

They were, first of all, calm; however, they changed their attitudes towards me after hearing the invective. They confiscated a few electronic device samples in my possession and talked me into calming down for smooth immigration.

I was immature. I should have talked to the staff gently and politely. If I had known the opening phrase then, I wouldn’t have been disgusted so much.

It was the second time I had gotten my samples confiscated on my overseas trip; I would say, loud and clear, nothing but a youthful indiscretion.

There are English words “factorize” and “garnish” in legal terms related to confiscation. I’m not a staffer of such authorities, but today, let me factorize not someone’s collateral for foreclosure but a quadratic formula in mathematics.

Factorize the quadratic formula \(x^{2} – 32x – y^{2} – 8y + 240\). (Ref: Enjoy Math to Become Mathy)

Here is my solution to the problem.

Apparently, it would be better to use a completing square.

\(x^{2} – 32x – y^{2} – 8y + 240\)
\(= \displaystyle\left\{(x – 16)^{2} – 256\right\} – \displaystyle\left\{(y + 4)^{2} – 16 – 240\right\}\)
\(= (x – 16)^{2} – (y + 4)^{2}\)
\(= (x + y – 12)(x – y – 20)\)

That’s one small step for a blogger, one giant leap for humanities-major persons.

Stay tuned, and expect to see my next post.

Keep well.

Frank Yoshida

￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣￣
【グローバルビジネスで役立つ数学】でもっと学習する b＾＾)
【参考図書】『もう一度高校数学』（著者：高橋一雄氏）株式会社日本実業出版社
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