Answer:
D
Step-by-step explanation:
Answer:
15x^2-3x-1
Step-by-step explanation:
All we have to do is collect like terms and calculate! Hope this helps!
(553-265)/48=6
6 hours spent repairing the car
Answer:
The rate of change in surface area when r = 20 cm is 20,106.19 cm²/min.
Step-by-step explanation:
The area of a sphere is given by the following formula:
![A = 4\pi r^{2}](https://tex.z-dn.net/?f=A%20%3D%204%5Cpi%20r%5E%7B2%7D)
In which A is the area, measured in cm², and r is the radius, measured in cm.
Assume that the radius r of a sphere is expanding at a rate of 40 cm/min.
This means that ![\frac{dr}{dt} = 40](https://tex.z-dn.net/?f=%5Cfrac%7Bdr%7D%7Bdt%7D%20%3D%2040)
Determine the rate of change in surface area when r = 20 cm.
This is
when
. So
![A = 4\pi r^{2}](https://tex.z-dn.net/?f=A%20%3D%204%5Cpi%20r%5E%7B2%7D)
Applying implicit differentiation.
We have two variables, A and r, so:
![\frac{dA}{dt} = 8r\pi \frac{dr}{dt}](https://tex.z-dn.net/?f=%5Cfrac%7BdA%7D%7Bdt%7D%20%3D%208r%5Cpi%20%5Cfrac%7Bdr%7D%7Bdt%7D)
![\frac{dA}{dt} = 8*20\pi*40](https://tex.z-dn.net/?f=%5Cfrac%7BdA%7D%7Bdt%7D%20%3D%208%2A20%5Cpi%2A40)
![\frac{dA}{dt} = 20106.19](https://tex.z-dn.net/?f=%5Cfrac%7BdA%7D%7Bdt%7D%20%3D%2020106.19)
The rate of change in surface area when r = 20 cm is 20,106.19 cm²/min.
Answer:
Explanation:
<u />
<u>1. First find the density of your chain</u>
- Volume = displaced water volume
= Volume of Final level of water - initial level of water
= 20 ml - 15 ml = 5 ml
- Density = 66.7g / 5 ml = 13.34 g/ml
<u />
<u>2. Second, write the denisty of the chain as the weighted average of the densities of the other metals:</u>
Mass of gold × density of gold + mass of other metals × density of other metals, all divided by the mass of the chain.
Calling x the amount of gold, then the amount of other metals is 66.7 - x:
![\dfrac{19.3\cdot x+9.7\cdot (66.7-x)}{66.7}=13.34](https://tex.z-dn.net/?f=%5Cdfrac%7B19.3%5Ccdot%20x%2B9.7%5Ccdot%20%2866.7-x%29%7D%7B66.7%7D%3D13.34)
![19.3x+635.66-9.7x=889.778](https://tex.z-dn.net/?f=19.3x%2B635.66-9.7x%3D889.778)
![9.6x=254.118\\\\x=26.47](https://tex.z-dn.net/?f=9.6x%3D254.118%5C%5C%5C%5Cx%3D26.47)
Then, there are 26.47 grams of gold in 66.7 grams of chain, which yields a percentage of:
- (26.47 / 66.7) × 100 = 39.7%