グローバルビジネスで役立つ数学（80）１次関数の決定（英語版）

Hi there!

――Examine the content, not the bottle.

That’s what I’ve repeatedly been underscoring for scrutinizing your counterparts in business. You shouldn’t judge a book by its cover, you know.

Then, what about your appearance? Needless to say, it is important to look polished and professional; however, you shouldn’t be too much flashy or look like you’re desperate to attract attention.

I wore a turquoise-color double-breasted suit with a gold bracelet when conducting business consultancy for export business. I drove to my clients and vendors in a sports car, whose social snobbery was part of my job.

To coincide with the consultancy, I kicked off teaching English at a vocational and language school, and one of my fellow teachers was flabbergasted to see my flashy appearance as if I were a winkler or dodgy businessperson amid a bubble economy.

For unfathomable reasons, I was about to turn my eyes to another business when my clients’ businesses showed signs of nosediving in the industry before long.

I’m the kind of person who can smell a rat about what’ll happen a few years down the road. It was regrettable that my guess hit it right on the nose, and their business was downward-sloping.

Truth be told, on October 1, 2022, I’ll quit teaching at a language school where I worked as a part-time instructor. Let’s see what’ll happen to them a few years later.

Today, let me challenge myself to find a linear function whose line graph shows downward-sloping. Hopefully, that is not the sales turnover of that school in a few years.

Find a linear function that satisfies the condition: its domain \(1 < x\leq 3\) and range \(-3\leq y < 3\). (Ref: Yellow Chart Math Ⅰ＋Ａ P85, slightly changed the condition)

Here is my solution to the problem.

Since the codomain includes not \(x = 1\) and \(y = 3\) but \(x = 3\) and \(y = -3\), the graph shows part of a straight line passing the two coordinates \((3, -3)\) and \((1, 3)\).

Plug the \((3, -3)\) and \((1, 3)\) in the linear function \(y = ax + b\), and we get \(a = -3\) and \(b = 6\).

Therefore, the linear function obtained is \(y = -3x + 6\,(1 < x\leq 3)\).

What about my business on online lessons? It’ll see “the writing on the wall” or, luckily, show “a positively sloped curve”?

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
【レッスン】私のオンライン英語レッスンをご希望の方はこちらをご覧ください。
【コンテント】当サイトで提供する情報はその正確性と最新性の確保に努めていま
　すが完全さを保証するものではありません。当サイトの内容に関するいかなる間
　違いについても一切の責任を負うものではありません。