Answer: 
Step-by-step explanation:
Given
Population of dust particle doubles every 30 minutes
If the initial sample is 21 grams
The model to predict the population will be

Where t=time in hours
A day has 24 hours . So, for 2 days time is 48 hours
Population is given by 
 
 
 
        
             
        
        
        
To expand two terms such as these, we can use the method called FOIL (stands for First, Outer, Inner, Last). Here is what I mean:
We have two terms: (x - 2)(x - 1)
We should first multiply the First two terms of each term in order to complete the F stage:
(x)*(x) = 

So then, we take the two outer terms and multiply them together to complete the O stage:
(x)*(-1) = -x
So far we have two things that we have calculated; at the end of the FOIL process we will have four.
To keep going with the FOIL, we now multiply the two inner terms to complete the I stage:
(-2)*(x) = -2x
Last but not least, we need to complete the L stage - so we multiply the two last terms of each term:
(-2)*(-1) = 2
Now that we have our four terms, let us add them together and combine like terms:

Since -x and -2x both have the x portion in common and they are added together, we can add them to create one single term:
-x + (-2x) = -3x
So now that we have our terms completed, we can combine into one polynomial equation:

 or 
 
 
        
        
        
Answer:
y=-3x+6
Step-by-step explanation:
that equation gives the answer for all the 'y'