See attachment for one such shell. The volume is given by the sum of infinitely many thin shells like this, each with radius

and height determined by the vertical distance between the upper blue curve and the lower orange curve for any given

, i.e.

.
The volume is then
The number of decorative pillows did the realtor arrange on each twin bed and queen bed is 6 and 9 respectively.
<h3>Simultaneous equation</h3>
let
- Number of decorative pillows for twin bed = x
- Number of decorative pillows for queen bed = y
x + y = 15
2x + y = 21
From equation (1)
x = 15 - y
- Substitute x = 15 - y into (2)
2x + y = 21
2(15 - y) + y = 21
30 - 2y + y = 21
- 2y + y = 21 - 30
-y = -9
y = 9
Substitute y = 9 into
x + y = 15
x + 9 = 15
x = 15 - 9
x = 6
Learn more about simultaneous equation:
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Answer:
x<−3+√1012 or x>−3−√1012
Step-by-step explanation:
I think it’s D, hope that helps