コーシーの関数方程式/Cauchy's functional equation

Knowing this result, you can solve various functional equations. Watch a video on the density of rational numbers here:    • 有理数の稠密性   I've started a subchannel called "Yobinori Takumi's Study Room" to share various knowledge:    / @ヨビノリたくみの自習室   ---------------------------------------------------------------------------------------------------------- [Yobinori Takumi's Book List] "I don't understand any of the complicated math formulas, but please teach me about differential and integral calculus!" https://amzn.to/33UvrRa →An introductory book on differential and integral calculus for the general public "I don't understand any of the complicated math formulas, but please teach me about the theory of relativity!" https://amzn.to/33Uh9Ae →An explanation of the theory of relativity that only uses easy middle school math "Learn college math in a cram school atmosphere" ~A Thorough Explanation of the Difficult Points" https://amzn.to/36cHj2N →This book compiles popular math topics from our videos. ---------------------------------------------------------------------------------------------------------- On the "University Math & Physics" channel, where you can learn in a cram school atmosphere, we upload video lessons for: ① University Course: University-level science subjects ② High School Course: Entrance exam-level science subjects We also provide a variety of information for high school and university science students. For business inquiries, please contact us on our website. For collaboration requests, please contact us on our website. For lecture requests, please leave a comment in the comments section of any video! Subscribe here:    / @yobinori   Official Website: http://yobinori.jp/ Twitter: (Actively active!) Takumi (Instructor) →   / yobinori   Yasu (Editor) →   / yasu_yobinori   Instagram: (I do Ogiri (comic comedy) shows) Takumi (Instructor) →   / yobinori   Yasu (Editor) →   / yobinoriyasu   Click here for [note] (I write serious articles) Takumi (Instructor) → https://note.mu/yobinori Yasu (Editor) → https://note.mu/yasu_yobinori ---------------------------------------------------------------------------------------------------------- [Special Sponsors] (Titles omitted) This channel is made possible by the support of our sponsors. [3000 yen/month] Suzuki Kantaro/CASTDICE TV/holdwine/Gon-chan/toshiro/F.Map!e/0990 Suddenly TOEIC [Wild TOEIC Course]/starting/eddy_breakup/★memotan★/Amber@'s Bells/Itacchi/Daily Memo/N. Chiba / 19masaru / sakamotoki / lysmet / Cebu IT x English study abroad "Kredo" / nakanot / Sako Yuki / Gengen / verdeviento / Isoda Shigeharu / Data Science VTuber Aisia = Solid / Abe Tetsuya / Kazulaser (*5000 yen) / Masa's High School Chemistry / Kohei Arai / koshiba.jp / oldboystudy30 (*3500 yen) / Taki Chihiro / oda_kyo / Yasutaro (*4000 yen) / Anko Kinako / Yada Tomoyuki (*4000 yen) / Sera Hideyuki / Ito Kensuke / Sagiya Narumi (*5000 yen) / Kanzaki Masaya / If you want to sell videos, use Filmuy / Samohan / Y. Hirai / Yoshi (*5000 yen) / N. Y. / Uchiyama Yuki @hottolink / Yamazaki Keiichiro / Moropee Anything Research Channel / Takama [¥1000/month] raxman (¥2000) / Komegi / Kiham / Quantum Solid / Fukutsuu / Kagami Tatsujin / Kogorou / Tsuyoshi Ono / Okaji / Piroshiki / CavitationVortex / Takayuki / Yuyuwalker / Shusuke Wakuda / log-1 / ksawaura / Yokonoito / sshirai / Keisuke Suita / Sugar / KzF / Takunologici / Gussan / Ryoto / Mitsui Jumpei / myai / Yuta Sakagami / Harahara745 / KBOY's Engineer TV / Manaka / hnokx / Kenta Mori from himeji/Okada Riku/anohitoooo/Tetsuyaiku/pajipaji/Shun/Moro/Bibi(..◜ᴗ◝..)bi/Kuma Power/Roki Festival/katz uz/Masahiro＠Information Processing Security Specialist/PhD/KenTag/Odeko/matpiano/Craft Beer (1500 yen)/STUDY PLACE Shochijuku/Kazu615/Shigeyoshi Hiro/takataka/Hirosaki University -Mathematics Club-/okinakosan/Watanabe/HorigomeDaisuke/fumaiinga/Ota Tax Accountant Office (Aomori City)/hyzksnj/etrlud/haruomaru/jeanjune/yottan [DIVE INTO CODE]/sn3y.com/Okamoto Produce/Tsuyoshi Tamura/Aoyama Acupuncture Clinic (Yoyogi)/Bonten Yutori/Takashi Kojima/Nobu/Hakase/Ebizo/T.uehara/Yyutak/nouvellelune Thank you for your continued support. We are looking for sponsors for Yobinori here (starting from 500 yen) ↓ https://camp-fire.jp/projects/view/13... *The above link URL uses an Amazon Associates link.