Answer:
the total amount of water supplier per hour to the region within a circle of radius R=110 ( that is from distance r, 0<r<110)
Step-by-step explanation:
if f(r) describes the water supplied at a distance r , the total amount supplied inside a region that goes from 0 until the circle of radius R, is the sum of all f(r) values from 0 until R, that is the integral value over these limits.
The formula deduction can be found in the attached picture
There is an "r" that multiplies e^-r as result of changing from rectangular coordinates to polar ones.(dx*dy --> r*dr*da)
Using the formula for the area of a triangle we can solve for the base.
The formula for area of a triangle is : Area = 1/2 x base x height
We are given the area and the height:
33.6 = 1/2 x 4 x base
Multiply both sides by 2 to remove the 1/2:
67.2 = 4 x base
Divide both sides by 4 to solve for the base:
67.2 /4 = 16.8
Check: Area = 1/2 x 4 x 16.8 = 33.6
The base is 16.8 inches.
Step-by-step explanation:
Solid paper costs 1.75 each
Printed paper costs 2.50 each
Given:
Ben = $43.50 (12 rolls solid paper and 9 rolls of printed paper)
Joel = $51.50 (8 rolls solid paper and 15 rolls of printed paper)
Let x = solid paper
Let y = printed paper
12x + 9y = 43.50
8x + 15y = 51.50
Find x:
8x + 15y = 51.50
8x = 51.50 - 15y
x = (51.50 - 15y)/8
Substitute x:
12x + 9y = 43.50
12(51.50 - 15y)/8 + 9y = 43.50
(618 - 180y)/8 + 9y = 43.50
8 (618 - 180y)/8 + 8*9y = 43.50 * 8
618 - 180y + 72y = 348
-108y = 348 - 618
-108y = -270
-108y/-108 = -270/-108
y = 2.50
x = (51.50 - 15y)/8
x = (51.50 - 15(2.5) /8
x = (51.50 - 37.50)/8
x = 14/8
x = 1.75
To check: x = 1.75 ; y = 2.5
12x + 9y = 43.50
12(1.75) + 9(2.5) = 43.50
21 + 22.50 = 43.50
43.50 = 43.50
8x + 15y = 51.50
8(1.75) + 15(2.5) = 51.50
14 + 37.50 = 51.50
51.50 = 51.50