Answer:
The rectangle is 7 km by 14 km. The 14 km dimension is parallel to the river.
Step-by-step explanation:
Let x represent the length of fence parallel to the river. The remaining fence is divided into two equal pieces for the ends of the enclosure. Then (28 -x)/2 will be the length of the side of the rectangle perpendicular to the river.
The total area of the enclosure is the product of length and width:
Area = (x)(28-x)/2
This expression describes a parabola opening downward with zeros at x=0 and x=28. The vertex (maximum) is halfway between those zeros, so is at ...
x = (0 +28)/2 = 14
Area is maximized when the dimension parallel to the river is 14 km and the ends of the enclosure are 7 km.
Answer:
9!=362880 ways
Step-by-step explanation:
It is given that there are 4 different mathematics books and 5 different science books.
So basically there are 9 different books. So we have 9 choices for the first book, 8 choices for the second book, since we have placed the first one. We have 7 choices for the third book and so on. Therefore, we can arrange 9 different books in,
!9 ways, on solving !9 we get,
So there are 362,880 ways to arrange 9 different books if there are no restrictions.