Answer:
2x
____
x+7
Step-by-step explanation:
1/4 + 1/4= 1/2
There are 2/4 in 1/2.
Hope this helps! :)
Answer:
Given that,
The number of grams A of a certain radioactive substance present at time, in years
from the present, t is given by the formula

a) To find the initial amount of this substance
At t=0, we get


We know that e^0=1 ( anything to the power zero is 1)
we get,

The initial amount of the substance is 45 grams
b)To find thehalf-life of this substance
To find t when the substance becames half the amount.
A=45/2
Substitute this we get,


Taking natural logarithm on both sides we get,







Half-life of this substance is 154.02
c) To find the amount of substance will be present around in 2500 years
Put t=2500
we get,




The amount of substance will be present around in 2500 years is 0.000585 grams
Option D: 3.47*10^-7 is the correct answer
Step-by-step explanation:
In order to determine the number written in standard scientific notation, first of all we have to understand how the scientific numbers are written
the scientific numbers are written in the form of:

Here
a is a number between 1 and 10 while the value of n can be only integer (positive or negative)
so,
In the given options:
Option A has a number larger than 10 in place of a so it is not in standard notation
Option B has a number less than 1 in place of a so it is also not in standard notation
Option C has a number larger than 10 in place of a so it is not in standard notation
Option D is in standard scientific notation as 1<3.47<10 and the power of 10 is integer
Hence,
Option D: 3.47*10^-7 is the correct answer
Keywords: Scientific notation, exponents
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