The answer is 16 2/3 as explained above
Answer:
<h2>
30 mm</h2>
Step-by-step explanation:
<h3>Hope it help </h3>
I assume this is the intersection of two lines, i.e. -1/2y is (-1/2)y. Please tell me if it's really -1/(2y).
(-1/2)y=(1/2)x+5
Multiplying both sides by -2
y = - x - 10
The other equation is
y = 2x + 2
We can equate them to find the meet
y = - x - 10 = 2x + 2
-3x = 12
x = -4
y = 2x + 2 = -6
Check: (-1/2)y=3, (1/2)x+5=3, equal, good
2x+2=2(-4)+2=-6=y, good
Answer: x=-4, y=-6
Answer:
The half-life of the radioactive substance is 135.9 hours.
Step-by-step explanation:
The rate of decay is proportional to the amount of the substance present at time t
This means that the amount of the substance can be modeled by the following differential equation:
![\frac{dQ}{dt} = -rt](https://tex.z-dn.net/?f=%5Cfrac%7BdQ%7D%7Bdt%7D%20%3D%20-rt)
Which has the following solution:
![Q(t) = Q(0)e^{-rt}](https://tex.z-dn.net/?f=Q%28t%29%20%3D%20Q%280%29e%5E%7B-rt%7D)
In which Q(t) is the amount after t hours, Q(0) is the initial amount and r is the decay rate.
After 6 hours the mass had decreased by 3%.
This means that
. We use this to find r.
![Q(t) = Q(0)e^{-rt}](https://tex.z-dn.net/?f=Q%28t%29%20%3D%20Q%280%29e%5E%7B-rt%7D)
![0.97Q(0) = Q(0)e^{-6r}](https://tex.z-dn.net/?f=0.97Q%280%29%20%3D%20Q%280%29e%5E%7B-6r%7D)
![e^{-6r} = 0.97](https://tex.z-dn.net/?f=e%5E%7B-6r%7D%20%3D%200.97)
![\ln{e^{-6r}} = \ln{0.97}](https://tex.z-dn.net/?f=%5Cln%7Be%5E%7B-6r%7D%7D%20%3D%20%5Cln%7B0.97%7D)
![-6r = \ln{0.97}](https://tex.z-dn.net/?f=-6r%20%3D%20%5Cln%7B0.97%7D)
![r = -\frac{\ln{0.97}}{6}](https://tex.z-dn.net/?f=r%20%3D%20-%5Cfrac%7B%5Cln%7B0.97%7D%7D%7B6%7D)
![r = 0.0051](https://tex.z-dn.net/?f=r%20%3D%200.0051)
So
![Q(t) = Q(0)e^{-0.0051t}](https://tex.z-dn.net/?f=Q%28t%29%20%3D%20Q%280%29e%5E%7B-0.0051t%7D)
Determine the half-life of the radioactive substance.
This is t for which Q(t) = 0.5Q(0). So
![Q(t) = Q(0)e^{-0.0051t}](https://tex.z-dn.net/?f=Q%28t%29%20%3D%20Q%280%29e%5E%7B-0.0051t%7D)
![0.5Q(0) = Q(0)e^{-0.0051t}](https://tex.z-dn.net/?f=0.5Q%280%29%20%3D%20Q%280%29e%5E%7B-0.0051t%7D)
![e^{-0.0051t} = 0.5](https://tex.z-dn.net/?f=e%5E%7B-0.0051t%7D%20%3D%200.5)
![\ln{e^{-0.0051t}} = \ln{0.5}](https://tex.z-dn.net/?f=%5Cln%7Be%5E%7B-0.0051t%7D%7D%20%3D%20%5Cln%7B0.5%7D)
![-0.0051t = \ln{0.5}](https://tex.z-dn.net/?f=-0.0051t%20%3D%20%5Cln%7B0.5%7D)
![t = -\frac{\ln{0.5}}{0.0051}](https://tex.z-dn.net/?f=t%20%3D%20-%5Cfrac%7B%5Cln%7B0.5%7D%7D%7B0.0051%7D)
![t = 135.9](https://tex.z-dn.net/?f=t%20%3D%20135.9)
The half-life of the radioactive substance is 135.9 hours.
Step-by-step explanation:
1/3x=1/6
x/3=1/6
cross multiply
6x=3
divide both sides by 6
x=3/6
x=1/2