Answer:
-3x
Step-by-step explanation:
this is the answer I think
Answer:
150.51 dB
Step-by-step explanation:
Data provided in the question:
decibel level of sound at 161 km distance = 180 dB
d₁ = 161 km
d₂ = 4800 km
I₁ = 180 db
The formula for intensity of sound is given as:
I = ![10\log(\frac{I_2}{I_1})](https://tex.z-dn.net/?f=10%5Clog%28%5Cfrac%7BI_2%7D%7BI_1%7D%29)
and the relation between intensity and distance is given as:
I ∝ ![\frac{1}{d^2}](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7Bd%5E2%7D)
or
Id² = constant
thus,
I₁d₁² = I₂d₂²
or
![\frac{I_2}{I_1}=\frac{d_1}{d_2}](https://tex.z-dn.net/?f=%5Cfrac%7BI_2%7D%7BI_1%7D%3D%5Cfrac%7Bd_1%7D%7Bd_2%7D)
therefore,
I = ![10\log(\frac{d_1}{d_2})^2](https://tex.z-dn.net/?f=10%5Clog%28%5Cfrac%7Bd_1%7D%7Bd_2%7D%29%5E2)
or
I = ![10\times2\times\log(\frac{161}{4,800})](https://tex.z-dn.net/?f=10%5Ctimes2%5Ctimes%5Clog%28%5Cfrac%7B161%7D%7B4%2C800%7D%29)
or
I = 20 × (-1.474)
or
I = -29.49
Therefore,
the decibel level on Rodriguez Island, 4,800 km away
= 180 - 29.49
= 150.51 dB
Answer: A
Step-by-step explanation:
![y=2x^2-8](https://tex.z-dn.net/?f=y%3D2x%5E2-8)
1. Swap x and y.
![x=2y^2-8](https://tex.z-dn.net/?f=x%3D2y%5E2-8)
2. Solve for the new y.
Add 8
![x+8=2y^2](https://tex.z-dn.net/?f=x%2B8%3D2y%5E2)
Divide by 2.
![\frac{x+8}{2}=y^2](https://tex.z-dn.net/?f=%5Cfrac%7Bx%2B8%7D%7B2%7D%3Dy%5E2)
Extract the square root.
![\sqrt{\frac{x+8}{2} }=y](https://tex.z-dn.net/?f=%5Csqrt%7B%5Cfrac%7Bx%2B8%7D%7B2%7D%20%7D%3Dy)
Answer:
u = 7
Step-by-step explanation:
-21 + 7u = 28
add 28 to both sides
7u = 49
divide by 7
u = 7