Answer:
-32
Step-by-step explanation:
Answer:
Step-by-step explanation:
The Answer is {x| x <-4 or x> 2}
Answer: 13) 6
I dont know 16 or 17
19) 33
Step-by-step explanation:
The area of the red part is greater than the area of the blue part.
Answer:
![r=1.05\ \text{ft}](https://tex.z-dn.net/?f=r%3D1.05%5C%20%5Ctext%7Bft%7D)
![h=2.12\ \text{ft}](https://tex.z-dn.net/?f=h%3D2.12%5C%20%5Ctext%7Bft%7D)
![20.91\ \text{ft}^3](https://tex.z-dn.net/?f=20.91%5C%20%5Ctext%7Bft%7D%5E3)
Step-by-step explanation:
r = Radius
h = Height
Volume of cylinder = ![7.35\ \text{ft}^3](https://tex.z-dn.net/?f=7.35%5C%20%5Ctext%7Bft%7D%5E3)
![V=\pi r^2h\\\Rightarrow h=\dfrac{V}{\pi r^2}\\\Rightarrow h=\dfrac{7.35}{\pi r^2}](https://tex.z-dn.net/?f=V%3D%5Cpi%20r%5E2h%5C%5C%5CRightarrow%20h%3D%5Cdfrac%7BV%7D%7B%5Cpi%20r%5E2%7D%5C%5C%5CRightarrow%20h%3D%5Cdfrac%7B7.35%7D%7B%5Cpi%20r%5E2%7D)
Surface area is given by
![A=2\pi r^2+2\pi rh\\\Rightarrow A=2\pi r^2+2\pi r\dfrac{7.35}{\pi r^2}\\\Rightarrow A=2\pi r^2+\dfrac{14.7}{r}](https://tex.z-dn.net/?f=A%3D2%5Cpi%20r%5E2%2B2%5Cpi%20rh%5C%5C%5CRightarrow%20A%3D2%5Cpi%20r%5E2%2B2%5Cpi%20r%5Cdfrac%7B7.35%7D%7B%5Cpi%20r%5E2%7D%5C%5C%5CRightarrow%20A%3D2%5Cpi%20r%5E2%2B%5Cdfrac%7B14.7%7D%7Br%7D)
Differentiating with respect to radius we get
![\dfrac{dA}{dr}=4\pi r-\dfrac{14.7}{r^2}](https://tex.z-dn.net/?f=%5Cdfrac%7BdA%7D%7Bdr%7D%3D4%5Cpi%20r-%5Cdfrac%7B14.7%7D%7Br%5E2%7D)
Equating with zero we get
![0=4\pi r-\dfrac{14.7}{r^2}\\\Rightarrow 4\pi r=\dfrac{14.7}{r^2}\\\Rightarrow r^3=\dfrac{14.7}{4\pi}\\\Rightarrow r=(\dfrac{14.7}{4\pi})^{\dfrac{1}{3}}\\\Rightarrow r=1.05](https://tex.z-dn.net/?f=0%3D4%5Cpi%20r-%5Cdfrac%7B14.7%7D%7Br%5E2%7D%5C%5C%5CRightarrow%204%5Cpi%20r%3D%5Cdfrac%7B14.7%7D%7Br%5E2%7D%5C%5C%5CRightarrow%20r%5E3%3D%5Cdfrac%7B14.7%7D%7B4%5Cpi%7D%5C%5C%5CRightarrow%20r%3D%28%5Cdfrac%7B14.7%7D%7B4%5Cpi%7D%29%5E%7B%5Cdfrac%7B1%7D%7B3%7D%7D%5C%5C%5CRightarrow%20r%3D1.05)
![\dfrac{d^2A}{dr^2}=4\pi-2\times \dfrac{14.7}{r^3}\\\Rightarrow \dfrac{d^2A}{dr^2}=4\pi+2\times \dfrac{14.7}{1.05^3}\\\Rightarrow \dfrac{d^2A}{dr^2}=37.96>0](https://tex.z-dn.net/?f=%5Cdfrac%7Bd%5E2A%7D%7Bdr%5E2%7D%3D4%5Cpi-2%5Ctimes%20%5Cdfrac%7B14.7%7D%7Br%5E3%7D%5C%5C%5CRightarrow%20%5Cdfrac%7Bd%5E2A%7D%7Bdr%5E2%7D%3D4%5Cpi%2B2%5Ctimes%20%5Cdfrac%7B14.7%7D%7B1.05%5E3%7D%5C%5C%5CRightarrow%20%5Cdfrac%7Bd%5E2A%7D%7Bdr%5E2%7D%3D37.96%3E0)
So, the value of the function is minimum at ![r=1.05](https://tex.z-dn.net/?f=r%3D1.05)
![h=\dfrac{7.35}{\pi r^2}=\dfrac{7.35}{\pi 1.05^2}\\\Rightarrow h=2.12](https://tex.z-dn.net/?f=h%3D%5Cdfrac%7B7.35%7D%7B%5Cpi%20r%5E2%7D%3D%5Cdfrac%7B7.35%7D%7B%5Cpi%201.05%5E2%7D%5C%5C%5CRightarrow%20h%3D2.12)
So, the radius and height which would minimize the surface area is 1.05 feet and 2.12 feet respectively.
Surface area
![A=2\pi r^2+2\pi rh\\\Rightarrow A=2\pi \times 1.05^2+2\pi 1.05\times 2.12\\\Rightarrow A=20.91\ \text{ft}^3](https://tex.z-dn.net/?f=A%3D2%5Cpi%20r%5E2%2B2%5Cpi%20rh%5C%5C%5CRightarrow%20A%3D2%5Cpi%20%5Ctimes%201.05%5E2%2B2%5Cpi%201.05%5Ctimes%202.12%5C%5C%5CRightarrow%20A%3D20.91%5C%20%5Ctext%7Bft%7D%5E3)
The minimum surface area is
.