Answer:
D
Step-by-step explanation:
Answer:
15.5
Step-by-step explanation:
You divide 62 by 2 which gives you 31 which means the car is going 31 mph. Then you divide 31 by 2 again and you get 15.5.
15.5
+15.5
-------
31.0
Hope I helped!!!
Answer:
x = -1
Step-by-step explanation:
<u>Answer-</u>
<em>The radius is increasing at a rate of
</em>
<u>Solution-</u>
The rate of change of the area of the crater is
, i.e
![\dfrac{dA}{dt}=\dfrac{\pi}{2}](https://tex.z-dn.net/?f=%5Cdfrac%7BdA%7D%7Bdt%7D%3D%5Cdfrac%7B%5Cpi%7D%7B2%7D)
We know that,
![Area =\pi r^2](https://tex.z-dn.net/?f=Area%20%3D%5Cpi%20r%5E2)
Putting this,
![\Rightarrow \dfrac{d(\pi r^2)}{dt}=\dfrac{\pi}{2}](https://tex.z-dn.net/?f=%5CRightarrow%20%5Cdfrac%7Bd%28%5Cpi%20r%5E2%29%7D%7Bdt%7D%3D%5Cdfrac%7B%5Cpi%7D%7B2%7D)
Applying chain rule,
![\Rightarrow \dfrac{d(\pi r^2)}{dr}\times \dfrac{dr}{dt}=\dfrac{\pi}{2}](https://tex.z-dn.net/?f=%5CRightarrow%20%5Cdfrac%7Bd%28%5Cpi%20r%5E2%29%7D%7Bdr%7D%5Ctimes%20%5Cdfrac%7Bdr%7D%7Bdt%7D%3D%5Cdfrac%7B%5Cpi%7D%7B2%7D)
![\Rightarrow (2\pi r)\times \dfrac{dr}{dt}=\dfrac{\pi}{2}](https://tex.z-dn.net/?f=%5CRightarrow%20%282%5Cpi%20r%29%5Ctimes%20%5Cdfrac%7Bdr%7D%7Bdt%7D%3D%5Cdfrac%7B%5Cpi%7D%7B2%7D)
Putting the value of radius as 4 (given),
![\Rightarrow 2\pi \times 4\times \dfrac{dr}{dt}=\dfrac{\pi}{2}](https://tex.z-dn.net/?f=%5CRightarrow%202%5Cpi%20%5Ctimes%204%5Ctimes%20%5Cdfrac%7Bdr%7D%7Bdt%7D%3D%5Cdfrac%7B%5Cpi%7D%7B2%7D)
![\Rightarrow 8\pi \dfrac{dr}{dt}=\dfrac{\pi}{2}](https://tex.z-dn.net/?f=%5CRightarrow%208%5Cpi%20%5Cdfrac%7Bdr%7D%7Bdt%7D%3D%5Cdfrac%7B%5Cpi%7D%7B2%7D)
![\Rightarrow \dfrac{dr}{dt}=\dfrac{\pi}{2\times 8\pi}](https://tex.z-dn.net/?f=%5CRightarrow%20%5Cdfrac%7Bdr%7D%7Bdt%7D%3D%5Cdfrac%7B%5Cpi%7D%7B2%5Ctimes%208%5Cpi%7D)
![\Rightarrow \dfrac{dr}{dt}=\dfrac{1}{16}](https://tex.z-dn.net/?f=%5CRightarrow%20%5Cdfrac%7Bdr%7D%7Bdt%7D%3D%5Cdfrac%7B1%7D%7B16%7D)