Answer:
It will take about 109.3 seconds for nine grams of the element to decay to 0.72 grams.
Step-by-step explanation:
We can write a half-life function to model our function.
A half-life function has the form:

Where <em>A₀</em> is the initial amount, <em>t</em> is the time that has passes (in this case seconds), <em>d</em> is the half-life, and <em>A</em> is the amount after <em>t</em> seconds.
Since the half-life of the element is 30 seconds, <em>d</em> = 30. Our initial sample has nine grams, so <em>A₀</em> is 9. Substitute:

We want to find the time it will take for the element to decay to 0.72 grams. So, we can let <em>A</em> = 0.72 and solve for <em>t: </em>
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Divide both sides by 9:

We can take the natural log of both sides:

By logarithm properties:

Solve for <em>t: </em>
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So, it will take about 109.3 seconds for nine grams of the element to decay to 0.72 grams.
Answer:
-2x+y=12
Step-by-step explanation:
linear equation
Answer:
y
4,
y ∈ [-∞, 4]
Step-by-step explanation:
Remember, the range of the function is all possible output values or y values.
As per the graph, it appears that the output, the y value, is less than or equal to 4. Hence:
y
4
or
y ∈ [-∞, 4]
is the range, both are the same, they are just different ways of writing it.
Answer:
A
Step-by-step explanation:
Just took the test :)
The answer is true, 1 mile is 5280 feet