Answer:
J and L
Step-by-step explanation:
I think the answer may be 54 but i'm not sure.
40x - 24 - 33x - 77 = 102
40x - 33x = 102 + 24 + 77
7x = 203
x = 29
Answer: Scalene means "a triangle that has three unequal sides"
therefore it is D
Answer:
![t = \frac{ln(\frac{21}{59})}{-0.15}=6.887 hr](https://tex.z-dn.net/?f=%20t%20%3D%20%5Cfrac%7Bln%28%5Cfrac%7B21%7D%7B59%7D%29%7D%7B-0.15%7D%3D6.887%20hr)
So it would takes approximately 6.9 hours to reach 32 F.
Step-by-step explanation:
For this case we have the following differential equationÑ
![\frac{du}{dt}= -k (u-T)](https://tex.z-dn.net/?f=%5Cfrac%7Bdu%7D%7Bdt%7D%3D%20-k%20%28u-T%29)
We can reorder the expression like this:
![\frac{du}{u-T} = -k dt](https://tex.z-dn.net/?f=%20%5Cfrac%7Bdu%7D%7Bu-T%7D%20%3D%20-k%20dt)
We can use the substitution
and
so then we have:
![\frac{dw}{w} =-k dt](https://tex.z-dn.net/?f=%20%5Cfrac%7Bdw%7D%7Bw%7D%20%3D-k%20dt)
IF we integrate both sides we got:
![ln |w| = -kt +C](https://tex.z-dn.net/?f=%20ln%20%7Cw%7C%20%3D%20-kt%20%2BC)
If we apply exponential in both sides we got:
![w = e^{-kt} *e^c](https://tex.z-dn.net/?f=%20w%20%3D%20e%5E%7B-kt%7D%20%2Ae%5Ec)
And if we replace w = u-T we got:
![u(t)= T + C_1 e^{-kt}](https://tex.z-dn.net/?f=%20u%28t%29%3D%20T%20%2B%20C_1%20e%5E%7B-kt%7D)
We can also express the solution in the following terms:
![u(t) = (T_i -T_{amb}) e^{kt} +T_{amb}](https://tex.z-dn.net/?f=%20u%28t%29%20%3D%20%28T_i%20-T_%7Bamb%7D%29%20e%5E%7Bkt%7D%20%2BT_%7Bamb%7D)
For this case we know that
since w ehave a cooloing,
, we have this model:
And if we want that the temperature would be 32F we can solve for t like this:
![32 = 59 e^{-0.15 t} +11](https://tex.z-dn.net/?f=%2032%20%3D%2059%20e%5E%7B-0.15%20t%7D%20%2B11)
![21=59 e^{-0.15 t}](https://tex.z-dn.net/?f=%2021%3D59%20e%5E%7B-0.15%20t%7D)
![\frac{21}{59} = e^{-0.15 t}](https://tex.z-dn.net/?f=%20%5Cfrac%7B21%7D%7B59%7D%20%3D%20e%5E%7B-0.15%20t%7D)
If we apply natural logs on both sides we got:
![ln (\frac{21}{59}) =-0.15 t](https://tex.z-dn.net/?f=%20ln%20%28%5Cfrac%7B21%7D%7B59%7D%29%20%3D-0.15%20t)
![t = \frac{ln(\frac{21}{59})}{-0.15}=6.887 hr](https://tex.z-dn.net/?f=%20t%20%3D%20%5Cfrac%7Bln%28%5Cfrac%7B21%7D%7B59%7D%29%7D%7B-0.15%7D%3D6.887%20hr)
So it would takes approximately 6.9 hours to reach 32 F.