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:

In which k is the decay rate.
The solution is:

In which Q(0) is the initial amount:
8000 counts per minute on a Geiger counter at a certain time
This means that 
500 counts per minute 13 days later.
This means that
. We use this to find k.







So

Determine the half-life of the radioactive substance.
This is t for which Q(t) = 0.5Q(0). So







The half-life of the radioactive substance is of 3.25 days.
Answer:
b ) a loan given for a short period of time that is not dependent on credit history
Step-by-step explanation:
:) enjoy
Answer:
B, C
Step-by-step explanation:
Since y=0, you are looking for equations such that 10 times the coefficient of x is the constant in the equation.
a) 5·10 ≠ 15
b) 2·10 = 20 . . . . select this one
c) 10 = 10 . . . . select this one
d) 3·10 ≠ 13
e) 4·10 ≠ 20
f) 6·10 ≠ 50
3x + 6= -1 - 3 + 4x
combine like terms
3x + 6= -4 + 4x
subtract 3x from both sides
6= -4 + x
add 4 to both sides
10= x
ANSWER: x= 10; This equation has one answer.
Hope this helps! :)