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elena55 [62]
3 years ago
5

Could someone help me with this?

Mathematics
1 answer:
Juli2301 [7.4K]3 years ago
4 0
(4,4)736472i would help but i jus points to do my homework lol
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Hello! Need help again
Shtirlitz [24]
Y=-x
Your welcome:):):)
4 0
3 years ago
9. Determine how long it takes for 80% of the material to decay.
Vilka [71]

Using an exponential function, it is found that it takes 18.6 days for 80% of the material to decay.

The amount of a substance after t days is modeled by:

A(t) = A(0)e^{-kt}

In which:

  • k is the decay rate, as a decimal.
  • A(0) is the initial amount.

The half-life is of 8 days, hence A(8) = 0.5A(0), and this is used to find k.

A(t) = A(0)e^{-kt}

0.5A(0) = A(0)e^{-8k}

e^{-8k} = 0.5

\ln{e^{-8k}} = \ln{0.5}

-8k = \ln{0.5}

k = -\frac{\ln{0.5}}{8}

k = 0.08664339757

Hence:

A(t) = A(0)e^{-0.08664339757t}

The time it takes for 80% of the material to decay it t for which A(t) = 0.2A(0), hence:

0.2A(0) = A(0)e^{-0.08664339757t}

e^{-0.08664339757t} = 0.2

\ln{e^{-0.08664339757t}} = \ln{0.2}

-0.08664339757t = \ln{0.2}

t = -\frac{\ln{0.2}}{0.08664339757}

t = 18.6

It takes 18.6 days for 80% of the material to decay.

To learn more about exponential functions, you can take a look at brainly.com/question/24906920

5 0
3 years ago
Five times the number of test tubes in a school’s chemistry lab exceeds three times the number of beakers it has by 660. The sum
GrogVix [38]
B= number of beakers which there are 450 
t= number of test tubes 
the answer is 1.46
8 0
3 years ago
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Marking brainliest <br><br> Please help
Ugo [173]
I think the answer is plus bc you need to add
5 0
3 years ago
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Robin read 63 books last year. She read 9 more books than
Stolb23 [73]

Answer: 54

Step-by-step explanation:

63-9 you can't take 9 away from 3 so you must borrow, the 6 becomes a 5 and the 3 becomes 13. 13-9 is 4, bring the 5 down and you have 54.

5 0
3 years ago
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