Answer: In June 2097
Step-by-step explanation:
According to the model, to find how many years t should take for 
we must solve the equation 
. Substracting 21100 from both sides, this equation is equivalent to 
.
Using the quadratic formula, the solutions are 
and 
. The solution 
can be neglected as the time t is a nonnegative number, therefore 
.
The value of t is approximately 85 and a half years and the initial time of this model is the January 1, 2012. Adding 85 years to the initial time gives the date January 2097, and finally adding the remaining half year (six months) we conclude that the date is June 2097.
The correct answer is D. Why?
In that phase of solving he can not know that integers on each side will be equal or not.
Good luck!!!
You can estimate 3.9 times 5.3 to 4 times 5 which is 20
so if the answer is around 20, you know that you will have exactly 2 digits before the decimal place
this is what I would come up with because.
y=the number of people infected
x=the number of days that have passed
1/3n - 8 = -13 <== ur equation
1/3n = -13 + 8
1/3n = - 5
n = -5 * 3
n = -15
check..
1/3(-15) - 8 = -13
-5 - 8 = -13
-13 = -13 (correct)
so the number (n) = -15
