quadratic equationとは 意味・読み方・使い方

名詞

quadratic equation (plural quadratic equations)

1. (algebra) A polynomial equation of the second degree; an equation that can be rearranged in standard form as ${\displaystyle ax^{2}+bx+c=0}$, where ${\displaystyle x}$ is an unknown value, ${\displaystyle a}$, ${\displaystyle b}$, and ${\displaystyle c}$ are known numbers, and where ${\displaystyle a}$ does not equal zero.

   Coordinate terms: linear equation, cubic equation

   • 2015 September 8, Katie Everson, “Why I've written a book for teenagers about taking drugs”, in The Guardian‎:

     When I was seven years old at a new school, I cried all day, every day. When I was 14 years old, I cried in maths lessons. An improvement, I guess. It wasn’t that I was bad at maths; I knew my way around a quadratic equation, let me tell you.

   • 2018 November 25, Kevin McKenna, “Remote island pub for sale ... just don’t expect a quiet life”, in The Guardian‎:

     The arid argot of the estate agent’s schedule becomes obsolete when the task is to sell a pub-restaurant at the edge of a Highland wilderness. It’s like trying to describe the glory of the Lake District with a quadratic equation.

   • 2020 February 5, Kenneth Chang, Jonathan Corum, “This Professor’s ‘Amazing’ Trick Makes Quadratic Equations Easier”, in The New York Times‎:

     The quadratic equation has frustrated math students for millenniums. […] If, while watching the Super Bowl, you had wanted to estimate how far a pass thrown by Patrick Mahomes traveled through the air, you would have been solving a quadratic equation.

   • 2024 April 8, Lydia Wang, Morgan Sullivan, Rachel Varina, “24 Best Hinge Prompts to Actually Help Your Matches Get to Know You”, in Cosmopolitan‎:

     If there’s one skill we absolutely should have been taught in school, it's how to craft the perfect dating app profile. I mean, if I can still remember the quadratic equation, surely I should have been schooled in the art of snagging a date. But alas, our education system seems to think finding our soulmates isn't as essential as algebra.

Further reading

• “quadratic equation, n.”, in OED Online ⁠, Oxford: Oxford University Press, launched 2000.
• “quadratic equation”, in Merriam-Webster Online Dictionary, Springfield, Mass.: Merriam-Webster, 1996–present.
• “quadratic equation”, in The American Heritage Dictionary of the English Language, 5th edition, Boston, Mass.: Houghton Mifflin Harcourt, 2016, →ISBN.