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.
Step-by-step explanation:
x= Number of small pages
y= Number of full pages
1 x + 1 y = 21 .............1
Total words
1200 x + 1500 y = 27000 .............2
Eliminate y
multiply (1)by -1500
Multiply (2) by 1
-1500 x -1500 y = -31500
1200 x + 1500 y = 27000
Add the two equations
-300 x = -4500
/ -300
x = 15
plug value of x in (1)
1 x + 1 y = 21
15 + y = 21
y = 21 -15
y = 6
y = 6
x= 15 Number of small pages
y= 6 Number of full pages
Answer:
First question -> y = 2
Second question -> y = 10
Step-by-step explanation:
<u>Step 1: Solve y + 2 = 4</u>
Subtract 2 from both sides
y + 2 - 2 = 4 - 2
<em>y = 2</em>
<em />
<u>Step 2: Solve y - 2 = 8</u>
Add 2 to both sides
y - 2 + 2 = 8 + 2
<em>y = 10</em>
<em />
Answer: First question -> y = 2
Second question -> y = 10
The answer would be 3.
In order to find this you must place the values in where you see the letters. So start with the letters and plug in.
mx - y
Since m = 1, put that in.
(1)x - y
Since x = 5, put that in
(1)(5) - y
Since y = 2, put that in
(1)(5) - (2)
Now follow the order of operations and solve
(1)(5) - 2
5 - 2
3