How Cauchy would find the maximum of sqrt(x)+sqrt(y)

Published: 03 September 2024
on channel: blackpenredpen
37,965
1.7k

Given x+2y=4, we want to find the maximum of sqrt(x)+sqrt(y). We can do this the Calculus 1 way (finding the critical number from the first derivative, then testing out if it's a min or max), but we can also use the Cauchy-Schwarz inequality. The version we will use is (a^2+b^2)(c^2+d^2) is greater than or equal to (ac+bd)^2. To read more, you can see
https://en.wikipedia.org/wiki/Cauchy%... Cauchy-Schwarz inequality is a big topic for high school students in Taiwan. It's definitely not easy sometimes but it is very cool.

The derivative way: Calculus 1: Given x+2y=4, find the max of sqrt(x)+sqrt(y)
   • Calculus 1: Given x+2y=4, find the ma...  

Here's a video that I did with Mr. Li when I was in Taiwan. Finding the maximum of 2/sin(theta)+3/cos(theta) for theta from 0 to pi/2 (這是我跟李翰老師 ‪@lihanmath‬ 合作影片之一. 這應該是台灣史上最有名的大學數學聯考題)    • 毫無準備,直接挑戰傳奇大學聯考題的樣子  
----------------------------------------
Big thanks to my Patrons for the full-marathon support!
Ben D, Grant S, Mark M, Phillippe S. Michael Z, Camille E.
Nolan C. Jan P. Devun C. Stefan C. Ethan BW
Didion S. NN Minkyu Y Brandon F

💪 Support this channel and get my math notes by becoming a patron:   / blackpenredpen  
🛍 Shop my math t-shirt & hoodies: https://amzn.to/3qBeuw6
----------------------------------------
#blackpenredpen #math #calculus #apcalculus


Watch video How Cauchy would find the maximum of sqrt(x)+sqrt(y) online without registration, duration hours minute second in high quality. This video was added by user blackpenredpen 03 September 2024, don't forget to share it with your friends and acquaintances, it has been viewed on our site 37,96 once and liked it 1.7 thousand people.