Calculus - Standalone book
Calculus - Standalone book
3rd Edition
ISBN: 9781464125263
Author: Jon Rogawski, Colin Adams
Publisher: W.H. Freeman & Co
bartleby

Concept explainers

bartleby

Videos

Question
Book Icon
Chapter 15.7, Problem 50E
To determine

That the rectangular box (including the top and bottom) of fixed volume and the smallest possible surface area is a cube.

Blurred answer
Students have asked these similar questions
Please find the open intervals where the functions are concave upward or concave downward. Find any inflection points also thanks!Note: This is a practice problem!
Use the graph below to evaluate each limit. -11 -10 -9 -8 -6 -5 -- + -0.3 -3 -2 -0.2 -0.1- ▼ 0 1 2 -0.1- -0.2- -0.3- 3. 4 5 -0 6 -0:4 -edit-graph-on- desmos lim f(x)= _9-←x lim f(x)⇒ x→1 ☐☐ lim f(x)⇒ +9-←x lim f(x)⇒ x→−4+ lim f(x)⇒ x→1+ lim f(x)= x→2+ lim f(x)⇒ x→-4 lim f(x)⇒ x→2
Please show your answer to 4 decimal places. Find the direction in which the maximum rate of change occurs for the function f(x, y) = 3x sin(xy) at the point (5,4). Give your answer as a unit vector.

Chapter 15 Solutions

Calculus - Standalone book

Ch. 15.1 - Prob. 6ECh. 15.1 - Prob. 7ECh. 15.1 - Prob. 8ECh. 15.1 - Prob. 9ECh. 15.1 - Prob. 10ECh. 15.1 - Prob. 11ECh. 15.1 - Prob. 12ECh. 15.1 - Prob. 13ECh. 15.1 - Prob. 14ECh. 15.1 - Prob. 15ECh. 15.1 - Prob. 16ECh. 15.1 - Prob. 17ECh. 15.1 - Prob. 18ECh. 15.1 - Prob. 19ECh. 15.1 - Prob. 20ECh. 15.1 - Prob. 21ECh. 15.1 - Prob. 22ECh. 15.1 - Prob. 23ECh. 15.1 - Prob. 24ECh. 15.1 - Prob. 25ECh. 15.1 - Prob. 26ECh. 15.1 - Prob. 27ECh. 15.1 - Prob. 28ECh. 15.1 - Prob. 29ECh. 15.1 - Prob. 30ECh. 15.1 - Prob. 31ECh. 15.1 - Prob. 32ECh. 15.1 - Prob. 33ECh. 15.1 - Prob. 34ECh. 15.1 - Prob. 35ECh. 15.1 - Prob. 36ECh. 15.1 - Prob. 37ECh. 15.1 - Prob. 38ECh. 15.1 - Prob. 39ECh. 15.1 - Prob. 40ECh. 15.1 - Prob. 41ECh. 15.1 - Prob. 42ECh. 15.1 - Prob. 43ECh. 15.1 - Prob. 44ECh. 15.1 - Prob. 45ECh. 15.1 - Prob. 46ECh. 15.1 - Prob. 47ECh. 15.1 - Prob. 48ECh. 15.1 - Prob. 49ECh. 15.1 - Prob. 50ECh. 15.1 - Prob. 51ECh. 15.1 - Prob. 52ECh. 15.1 - Prob. 53ECh. 15.1 - Prob. 54ECh. 15.1 - Prob. 55ECh. 15.1 - Prob. 56ECh. 15.1 - Prob. 57ECh. 15.2 - Prob. 1PQCh. 15.2 - Prob. 2PQCh. 15.2 - Prob. 3PQCh. 15.2 - Prob. 4PQCh. 15.2 - Prob. 1ECh. 15.2 - Prob. 2ECh. 15.2 - Prob. 3ECh. 15.2 - Prob. 4ECh. 15.2 - Prob. 5ECh. 15.2 - Prob. 6ECh. 15.2 - Prob. 7ECh. 15.2 - Prob. 8ECh. 15.2 - Prob. 9ECh. 15.2 - Prob. 10ECh. 15.2 - Prob. 11ECh. 15.2 - Prob. 12ECh. 15.2 - Prob. 13ECh. 15.2 - Prob. 14ECh. 15.2 - Prob. 15ECh. 15.2 - Prob. 16ECh. 15.2 - Prob. 17ECh. 15.2 - Prob. 18ECh. 15.2 - Prob. 19ECh. 15.2 - Prob. 20ECh. 15.2 - Prob. 21ECh. 15.2 - Prob. 22ECh. 15.2 - Prob. 23ECh. 15.2 - Prob. 24ECh. 15.2 - Prob. 25ECh. 15.2 - Prob. 26ECh. 15.2 - Prob. 27ECh. 15.2 - Prob. 28ECh. 15.2 - Prob. 29ECh. 15.2 - Prob. 30ECh. 15.2 - Prob. 31ECh. 15.2 - Prob. 32ECh. 15.2 - Prob. 33ECh. 15.2 - Prob. 34ECh. 15.2 - Prob. 35ECh. 15.2 - Prob. 36ECh. 15.2 - Prob. 37ECh. 15.2 - Prob. 38ECh. 15.2 - Prob. 39ECh. 15.2 - Prob. 40ECh. 15.2 - Prob. 41ECh. 15.2 - Prob. 42ECh. 15.2 - Prob. 43ECh. 15.2 - Prob. 44ECh. 15.2 - Prob. 45ECh. 15.2 - Prob. 46ECh. 15.2 - Prob. 47ECh. 15.2 - Prob. 48ECh. 15.2 - Prob. 49ECh. 15.3 - Prob. 1PQCh. 15.3 - Prob. 2PQCh. 15.3 - Prob. 3PQCh. 15.3 - Prob. 4PQCh. 15.3 - Prob. 5PQCh. 15.3 - Prob. 1ECh. 15.3 - Prob. 2ECh. 15.3 - Prob. 3ECh. 15.3 - Prob. 4ECh. 15.3 - Prob. 5ECh. 15.3 - Prob. 6ECh. 15.3 - Prob. 7ECh. 15.3 - Prob. 8ECh. 15.3 - Prob. 9ECh. 15.3 - Prob. 10ECh. 15.3 - Prob. 11ECh. 15.3 - Prob. 12ECh. 15.3 - Prob. 13ECh. 15.3 - Prob. 14ECh. 15.3 - Prob. 15ECh. 15.3 - Prob. 16ECh. 15.3 - Prob. 17ECh. 15.3 - Prob. 18ECh. 15.3 - Prob. 19ECh. 15.3 - Prob. 20ECh. 15.3 - Prob. 21ECh. 15.3 - Prob. 22ECh. 15.3 - Prob. 23ECh. 15.3 - Prob. 24ECh. 15.3 - Prob. 25ECh. 15.3 - Prob. 26ECh. 15.3 - Prob. 27ECh. 15.3 - Prob. 28ECh. 15.3 - Prob. 29ECh. 15.3 - Prob. 30ECh. 15.3 - Prob. 31ECh. 15.3 - Prob. 32ECh. 15.3 - Prob. 33ECh. 15.3 - Prob. 34ECh. 15.3 - Prob. 35ECh. 15.3 - Prob. 36ECh. 15.3 - Prob. 37ECh. 15.3 - Prob. 38ECh. 15.3 - Prob. 39ECh. 15.3 - Prob. 40ECh. 15.3 - Prob. 41ECh. 15.3 - Prob. 42ECh. 15.3 - Prob. 43ECh. 15.3 - Prob. 44ECh. 15.3 - Prob. 45ECh. 15.3 - Prob. 46ECh. 15.3 - Prob. 47ECh. 15.3 - Prob. 48ECh. 15.3 - Prob. 49ECh. 15.3 - Prob. 50ECh. 15.3 - Prob. 51ECh. 15.3 - Prob. 52ECh. 15.3 - Prob. 53ECh. 15.3 - Prob. 54ECh. 15.3 - Prob. 55ECh. 15.3 - Prob. 56ECh. 15.3 - Prob. 57ECh. 15.3 - Prob. 58ECh. 15.3 - Prob. 59ECh. 15.3 - Prob. 60ECh. 15.3 - Prob. 61ECh. 15.3 - Prob. 62ECh. 15.3 - Prob. 63ECh. 15.3 - Prob. 64ECh. 15.3 - Prob. 65ECh. 15.3 - Prob. 66ECh. 15.3 - Prob. 67ECh. 15.3 - Prob. 68ECh. 15.3 - Prob. 69ECh. 15.3 - Prob. 70ECh. 15.3 - Prob. 71ECh. 15.3 - Prob. 72ECh. 15.3 - Prob. 73ECh. 15.3 - Prob. 74ECh. 15.3 - Prob. 75ECh. 15.3 - Prob. 76ECh. 15.3 - Prob. 77ECh. 15.3 - Prob. 78ECh. 15.3 - Prob. 79ECh. 15.3 - Prob. 80ECh. 15.3 - Prob. 81ECh. 15.3 - Prob. 82ECh. 15.3 - Prob. 83ECh. 15.3 - Prob. 84ECh. 15.4 - Prob. 1PQCh. 15.4 - Prob. 2PQCh. 15.4 - Prob. 3PQCh. 15.4 - Prob. 4PQCh. 15.4 - Prob. 5PQCh. 15.4 - Prob. 6PQCh. 15.4 - Prob. 1ECh. 15.4 - Prob. 2ECh. 15.4 - Prob. 3ECh. 15.4 - Prob. 4ECh. 15.4 - Prob. 5ECh. 15.4 - Prob. 6ECh. 15.4 - Prob. 7ECh. 15.4 - Prob. 8ECh. 15.4 - Prob. 9ECh. 15.4 - Prob. 10ECh. 15.4 - Prob. 11ECh. 15.4 - Prob. 12ECh. 15.4 - Prob. 13ECh. 15.4 - Prob. 14ECh. 15.4 - Prob. 15ECh. 15.4 - Prob. 16ECh. 15.4 - Prob. 17ECh. 15.4 - Prob. 18ECh. 15.4 - Prob. 19ECh. 15.4 - Prob. 20ECh. 15.4 - Prob. 21ECh. 15.4 - Prob. 22ECh. 15.4 - Prob. 23ECh. 15.4 - Prob. 24ECh. 15.4 - Prob. 25ECh. 15.4 - Prob. 26ECh. 15.4 - Prob. 27ECh. 15.4 - Prob. 28ECh. 15.4 - Prob. 29ECh. 15.4 - Prob. 30ECh. 15.4 - Prob. 31ECh. 15.4 - Prob. 32ECh. 15.4 - Prob. 33ECh. 15.4 - Prob. 34ECh. 15.4 - Prob. 35ECh. 15.4 - Prob. 36ECh. 15.4 - Prob. 37ECh. 15.4 - Prob. 38ECh. 15.4 - Prob. 39ECh. 15.4 - Prob. 40ECh. 15.4 - Prob. 41ECh. 15.4 - Prob. 42ECh. 15.4 - Prob. 43ECh. 15.4 - Prob. 44ECh. 15.4 - Prob. 45ECh. 15.5 - Prob. 1PQCh. 15.5 - Prob. 2PQCh. 15.5 - Prob. 3PQCh. 15.5 - Prob. 4PQCh. 15.5 - Prob. 5PQCh. 15.5 - Prob. 1ECh. 15.5 - Prob. 2ECh. 15.5 - Prob. 3ECh. 15.5 - Prob. 4ECh. 15.5 - Prob. 5ECh. 15.5 - Prob. 6ECh. 15.5 - Prob. 7ECh. 15.5 - Prob. 8ECh. 15.5 - Prob. 9ECh. 15.5 - Prob. 10ECh. 15.5 - Prob. 11ECh. 15.5 - Prob. 12ECh. 15.5 - Prob. 13ECh. 15.5 - Prob. 14ECh. 15.5 - Prob. 15ECh. 15.5 - Prob. 16ECh. 15.5 - Prob. 17ECh. 15.5 - Prob. 18ECh. 15.5 - Prob. 19ECh. 15.5 - Prob. 20ECh. 15.5 - Prob. 21ECh. 15.5 - Prob. 22ECh. 15.5 - Prob. 23ECh. 15.5 - Prob. 24ECh. 15.5 - Prob. 25ECh. 15.5 - Prob. 26ECh. 15.5 - Prob. 27ECh. 15.5 - Prob. 28ECh. 15.5 - Prob. 29ECh. 15.5 - Prob. 30ECh. 15.5 - Prob. 31ECh. 15.5 - Prob. 32ECh. 15.5 - Prob. 33ECh. 15.5 - Prob. 34ECh. 15.5 - Prob. 35ECh. 15.5 - Prob. 36ECh. 15.5 - Prob. 37ECh. 15.5 - Prob. 38ECh. 15.5 - Prob. 39ECh. 15.5 - Prob. 40ECh. 15.5 - Prob. 41ECh. 15.5 - Prob. 42ECh. 15.5 - Prob. 43ECh. 15.5 - Prob. 44ECh. 15.5 - Prob. 45ECh. 15.5 - Prob. 46ECh. 15.5 - Prob. 47ECh. 15.5 - Prob. 48ECh. 15.5 - Prob. 50ECh. 15.5 - Prob. 51ECh. 15.5 - Prob. 52ECh. 15.5 - Prob. 53ECh. 15.5 - Prob. 54ECh. 15.5 - Prob. 55ECh. 15.5 - Prob. 56ECh. 15.5 - Prob. 57ECh. 15.5 - Prob. 58ECh. 15.5 - Prob. 59ECh. 15.5 - Prob. 60ECh. 15.5 - Prob. 61ECh. 15.5 - Prob. 62ECh. 15.5 - Prob. 63ECh. 15.5 - Prob. 64ECh. 15.5 - Prob. 65ECh. 15.5 - Prob. 66ECh. 15.5 - Prob. 67ECh. 15.5 - Prob. 68ECh. 15.5 - Prob. 69ECh. 15.5 - Prob. 70ECh. 15.5 - Prob. 71ECh. 15.5 - Prob. 72ECh. 15.5 - Prob. 73ECh. 15.5 - Prob. 74ECh. 15.5 - Prob. 75ECh. 15.6 - Prob. 1PQCh. 15.6 - Prob. 2PQCh. 15.6 - Prob. 3PQCh. 15.6 - Prob. 4PQCh. 15.6 - Prob. 5PQCh. 15.6 - Prob. 1ECh. 15.6 - Prob. 2ECh. 15.6 - Prob. 3ECh. 15.6 - Prob. 4ECh. 15.6 - Prob. 5ECh. 15.6 - Prob. 6ECh. 15.6 - Prob. 7ECh. 15.6 - Prob. 8ECh. 15.6 - Prob. 9ECh. 15.6 - Prob. 10ECh. 15.6 - Prob. 11ECh. 15.6 - Prob. 12ECh. 15.6 - Prob. 13ECh. 15.6 - Prob. 14ECh. 15.6 - Prob. 15ECh. 15.6 - Prob. 16ECh. 15.6 - Prob. 17ECh. 15.6 - Prob. 18ECh. 15.6 - Prob. 19ECh. 15.6 - Prob. 20ECh. 15.6 - Prob. 21ECh. 15.6 - Prob. 22ECh. 15.6 - Prob. 23ECh. 15.6 - Prob. 24ECh. 15.6 - Prob. 25ECh. 15.6 - Prob. 26ECh. 15.6 - Prob. 27ECh. 15.6 - Prob. 28ECh. 15.6 - Prob. 29ECh. 15.6 - Prob. 30ECh. 15.6 - Prob. 31ECh. 15.6 - Prob. 32ECh. 15.6 - Prob. 33ECh. 15.6 - Prob. 34ECh. 15.6 - Prob. 35ECh. 15.6 - Prob. 36ECh. 15.6 - Prob. 37ECh. 15.6 - Prob. 38ECh. 15.6 - Prob. 39ECh. 15.6 - Prob. 40ECh. 15.6 - Prob. 41ECh. 15.6 - Prob. 42ECh. 15.6 - Prob. 43ECh. 15.6 - Prob. 44ECh. 15.6 - Prob. 45ECh. 15.6 - Prob. 46ECh. 15.6 - Prob. 47ECh. 15.6 - Prob. 48ECh. 15.6 - Prob. 49ECh. 15.6 - Prob. 50ECh. 15.6 - Prob. 51ECh. 15.6 - Prob. 52ECh. 15.6 - Prob. 53ECh. 15.7 - Prob. 1PQCh. 15.7 - Prob. 2PQCh. 15.7 - Prob. 3PQCh. 15.7 - Prob. 1ECh. 15.7 - Prob. 2ECh. 15.7 - Prob. 3ECh. 15.7 - Prob. 4ECh. 15.7 - Prob. 5ECh. 15.7 - Prob. 6ECh. 15.7 - Prob. 7ECh. 15.7 - Prob. 8ECh. 15.7 - Prob. 9ECh. 15.7 - Prob. 10ECh. 15.7 - Prob. 11ECh. 15.7 - Prob. 12ECh. 15.7 - Prob. 13ECh. 15.7 - Prob. 14ECh. 15.7 - Prob. 15ECh. 15.7 - Prob. 16ECh. 15.7 - Prob. 17ECh. 15.7 - Prob. 18ECh. 15.7 - Prob. 19ECh. 15.7 - Prob. 20ECh. 15.7 - Prob. 21ECh. 15.7 - Prob. 22ECh. 15.7 - Prob. 23ECh. 15.7 - Prob. 24ECh. 15.7 - Prob. 25ECh. 15.7 - Prob. 26ECh. 15.7 - Prob. 27ECh. 15.7 - Prob. 28ECh. 15.7 - Prob. 29ECh. 15.7 - Prob. 30ECh. 15.7 - Prob. 31ECh. 15.7 - Prob. 32ECh. 15.7 - Prob. 33ECh. 15.7 - Prob. 34ECh. 15.7 - Prob. 35ECh. 15.7 - Prob. 36ECh. 15.7 - Prob. 37ECh. 15.7 - Prob. 38ECh. 15.7 - Prob. 39ECh. 15.7 - Prob. 40ECh. 15.7 - Prob. 41ECh. 15.7 - Prob. 42ECh. 15.7 - Prob. 43ECh. 15.7 - Prob. 44ECh. 15.7 - Prob. 45ECh. 15.7 - Prob. 46ECh. 15.7 - Prob. 47ECh. 15.7 - Prob. 48ECh. 15.7 - Prob. 49ECh. 15.7 - Prob. 50ECh. 15.7 - Prob. 51ECh. 15.7 - Prob. 52ECh. 15.7 - Prob. 53ECh. 15.7 - Prob. 54ECh. 15.7 - Prob. 55ECh. 15.7 - Prob. 56ECh. 15.7 - Prob. 57ECh. 15.7 - Prob. 58ECh. 15.7 - Prob. 59ECh. 15.7 - Prob. 60ECh. 15.8 - Prob. 1PQCh. 15.8 - Prob. 2PQCh. 15.8 - Prob. 3PQCh. 15.8 - Prob. 1ECh. 15.8 - Prob. 2ECh. 15.8 - Prob. 3ECh. 15.8 - Prob. 4ECh. 15.8 - Prob. 5ECh. 15.8 - Prob. 6ECh. 15.8 - Prob. 7ECh. 15.8 - Prob. 8ECh. 15.8 - Prob. 9ECh. 15.8 - Prob. 10ECh. 15.8 - Prob. 11ECh. 15.8 - Prob. 12ECh. 15.8 - Prob. 13ECh. 15.8 - Prob. 14ECh. 15.8 - Prob. 15ECh. 15.8 - Prob. 16ECh. 15.8 - Prob. 17ECh. 15.8 - Prob. 18ECh. 15.8 - Prob. 19ECh. 15.8 - Prob. 20ECh. 15.8 - Prob. 21ECh. 15.8 - Prob. 22ECh. 15.8 - Prob. 23ECh. 15.8 - Prob. 24ECh. 15.8 - Prob. 25ECh. 15.8 - Prob. 26ECh. 15.8 - Prob. 27ECh. 15.8 - Prob. 28ECh. 15.8 - Prob. 29ECh. 15.8 - Prob. 30ECh. 15.8 - Prob. 31ECh. 15.8 - Prob. 32ECh. 15.8 - Prob. 33ECh. 15.8 - Prob. 34ECh. 15.8 - Prob. 35ECh. 15.8 - Prob. 36ECh. 15.8 - Prob. 37ECh. 15.8 - Prob. 38ECh. 15.8 - Prob. 39ECh. 15.8 - Prob. 40ECh. 15.8 - Prob. 41ECh. 15.8 - Prob. 42ECh. 15.8 - Prob. 43ECh. 15.8 - Prob. 44ECh. 15.8 - Prob. 45ECh. 15.8 - Prob. 46ECh. 15.8 - Prob. 47ECh. 15.8 - Prob. 48ECh. 15.8 - Prob. 49ECh. 15.8 - Prob. 50ECh. 15.8 - Prob. 51ECh. 15.8 - Prob. 52ECh. 15.8 - Prob. 53ECh. 15.8 - Prob. 54ECh. 15.8 - Prob. 55ECh. 15.8 - Prob. 56ECh. 15 - Prob. 1CRECh. 15 - Prob. 2CRECh. 15 - Prob. 3CRECh. 15 - Prob. 4CRECh. 15 - Prob. 5CRECh. 15 - Prob. 6CRECh. 15 - Prob. 7CRECh. 15 - Prob. 8CRECh. 15 - Prob. 9CRECh. 15 - Prob. 10CRECh. 15 - Prob. 11CRECh. 15 - Prob. 12CRECh. 15 - Prob. 13CRECh. 15 - Prob. 14CRECh. 15 - Prob. 15CRECh. 15 - Prob. 16CRECh. 15 - Prob. 17CRECh. 15 - Prob. 18CRECh. 15 - Prob. 19CRECh. 15 - Prob. 20CRECh. 15 - Prob. 21CRECh. 15 - Prob. 22CRECh. 15 - Prob. 23CRECh. 15 - Prob. 24CRECh. 15 - Prob. 25CRECh. 15 - Prob. 26CRECh. 15 - Prob. 27CRECh. 15 - Prob. 28CRECh. 15 - Prob. 29CRECh. 15 - Prob. 30CRECh. 15 - Prob. 31CRECh. 15 - Prob. 32CRECh. 15 - Prob. 33CRECh. 15 - Prob. 34CRECh. 15 - Prob. 35CRECh. 15 - Prob. 36CRECh. 15 - Prob. 37CRECh. 15 - Prob. 38CRECh. 15 - Prob. 39CRECh. 15 - Prob. 40CRECh. 15 - Prob. 41CRECh. 15 - Prob. 42CRECh. 15 - Prob. 43CRECh. 15 - Prob. 44CRECh. 15 - Prob. 45CRECh. 15 - Prob. 46CRECh. 15 - Prob. 47CRECh. 15 - Prob. 48CRECh. 15 - Prob. 49CRECh. 15 - Prob. 50CRECh. 15 - Prob. 51CRECh. 15 - Prob. 52CRECh. 15 - Prob. 53CRECh. 15 - Prob. 54CRECh. 15 - Prob. 55CRECh. 15 - Prob. 56CRECh. 15 - Prob. 57CRECh. 15 - Prob. 58CRECh. 15 - Prob. 59CRECh. 15 - Prob. 60CRECh. 15 - Prob. 61CRECh. 15 - Prob. 62CRECh. 15 - Prob. 63CRE
Knowledge Booster
Background pattern image
Calculus
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, calculus and related others by exploring similar questions and additional content below.
Similar questions
SEE MORE QUESTIONS
Recommended textbooks for you
Text book image
Elementary Geometry For College Students, 7e
Geometry
ISBN:9781337614085
Author:Alexander, Daniel C.; Koeberlein, Geralyn M.
Publisher:Cengage,
Text book image
Algebra: Structure And Method, Book 1
Algebra
ISBN:9780395977224
Author:Richard G. Brown, Mary P. Dolciani, Robert H. Sorgenfrey, William L. Cole
Publisher:McDougal Littell
Text book image
PREALGEBRA
Algebra
ISBN:9781938168994
Author:OpenStax
Publisher:OpenStax
Text book image
Elementary Geometry for College Students
Geometry
ISBN:9781285195698
Author:Daniel C. Alexander, Geralyn M. Koeberlein
Publisher:Cengage Learning
Text book image
Mathematics For Machine Technology
Advanced Math
ISBN:9781337798310
Author:Peterson, John.
Publisher:Cengage Learning,
Text book image
Holt Mcdougal Larson Pre-algebra: Student Edition...
Algebra
ISBN:9780547587776
Author:HOLT MCDOUGAL
Publisher:HOLT MCDOUGAL
Area Between The Curve Problem No 1 - Applications Of Definite Integration - Diploma Maths II; Author: Ekeeda;https://www.youtube.com/watch?v=q3ZU0GnGaxA;License: Standard YouTube License, CC-BY