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Alex787 [66]
4 years ago
11

Can you please help me with pre-algebra?? :)

Mathematics
1 answer:
Lesechka [4]4 years ago
5 0
I will always be available to answer any of you're questions you can trust me I am the smartest in my class
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Diane is on her way home in her car. She has driven 12 miles so far, which is three-fourths of the way home. What is the total l
andrew-mc [135]

16miles left

Step-by-step explanation:

7 0
3 years ago
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Helen wrote the following facts to try to show that division by 0 results in 0. Explain her error.
earnstyle [38]

Helen should of put 0 first, because if you're gonna divide, you need to put the product first, then one of the factoes.

So instead it should be 0÷(-7)=0

3 0
3 years ago
Find the fourth root of 81 that<br> graphs on the positive y-axis.
klio [65]

Answer:

1.732

Step-by-step explanation:

cube root of 81 is

=1.732

3 0
3 years ago
Suppose an unknown radioactive substance produces 8000 counts per minute on a Geiger counter at a certain time, and only 500 cou
mariarad [96]

Answer:

The half-life of the radioactive substance is of 3.25 days.

Step-by-step explanation:

The amount of radioactive substance is proportional to the number of counts per minute:

This means that the amount is given by the following differential equation:

\frac{dQ}{dt} = -kQ

In which k is the decay rate.

The solution is:

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

In which Q(0) is the initial amount:

8000 counts per minute on a Geiger counter at a certain time

This means that Q(0) = 8000

500 counts per minute 13 days later.

This means that Q(13) = 500. We use this to find k.

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

500 = 8000e^{-13k}

e^{-13k} = \frac{500}{8000}

\ln{e^{-13k}} = \ln{\frac{500}{8000}}

-13k = \ln{\frac{500}{8000}}

k = -\frac{\ln{\frac{500}{8000}}}{13}

k = 0.2133

So

Q(t) = Q(0)e^{-0.2133t}

Determine the half-life of the radioactive substance.

This is t for which Q(t) = 0.5Q(0). So

Q(t) = Q(0)e^{-0.2133t}

0.5Q(0) = Q(0)e^{-0.2133t}

e^{-0.2133t} = 0.5

\ln{e^{-0.2133t}} = \ln{0.5}

-0.2133t = \ln{0.5}

t = -\frac{\ln{0.5}}{0.2133}

t = 3.25

The half-life of the radioactive substance is of 3.25 days.

7 0
3 years ago
Evaluate.<br><br> 4 to the power of 3 + (-2) to the power of 4
finlep [7]

Answer:

4

Step-by-step explanation:

3+(-2) is the same as 3-2 which is 1. and since with multiple exponents you work from the top you have 4 to the power of 1^4. 1^4 is 1, so it's 4^1, which is 4.

3 0
2 years ago
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