#### [Calculus] Function regarding distance from (0,0) to another function

Timothy Lee

0

So I picked this (translated) Calculus book by Thomas from library to refresh some math and in here after the first chapter about functions there is this question which I understand and know the answer to (thanks to the solutions part of the book), but I don't know how to do it myself (even a first step would be welcome). So it's not really homework, but I hope this is still the right place to ask. I would be grateful for any help. Thanks. Here a rough translation: You got 2x+4y=5 as a graph with the point (x,y). L(x) is the function that links the distance of any (x,y) to (0,0). Present function L(x). Answer: L = sqrt(20x^2 - 20x + 25) / 4