University of the District of Columbia Linear Algebra Questions

Answer two questions for differential equation with linear algebra

Please see the attachment to see the questions.

Question 4
According to a recent data analysis, the amount A(t) of atmospheric pollutants in a certain city is found to approximately quadruple every 8.5 years. The current amount of
pollution in this city is 18 pu (pollutant units), and it is considered to be dangerous to stay in the city when the amount of pollutants reaches 135 pu.
Applying the differential equation model: (dA/dt) = KA, (k>0)
approximately, how long do the residents of this city have before the dangerous limit is reached?
13.86 years
O a.
10.72 years
Ob.
11.25 years
Oc.
O d. 9.85 years
12.35 years
O e.
14.23 years
Of.
Question 5
Consider the following system of linear equations:
x + 3y + 3z = a
2x + 5y + 4z = b
2x + 7y + 8z = C
Which, if any, of the following statements is true?
a None of the given answers is correct.
.
b. The linear system has a unique solution if 2a + c = 0.
c.
The linear system has no solution if b + c > 4a.
d. The linear system has a unique solution if – 2a + b + c = 0
The linear system has an infinite number of solutions if b + c = 4a.
Of. The linear system has no solution if b + c < 4a . Question 4 According to a recent data analysis, the amount A(t) of atmospheric pollutants in a certain city is found to approximately quadruple every 8.5 years. The current amount of pollution in this city is 18 pu (pollutant units), and it is considered to be dangerous to stay in the city when the amount of pollutants reaches 135 pu. Applying the differential equation model: (dA/dt) = KA, (k>0)
approximately, how long do the residents of this city have before the dangerous limit is reached?
13.86 years
O a.
10.72 years
Ob.
11.25 years
Oc.
O d. 9.85 years
12.35 years
O e.
14.23 years
Of.
Question 5
Consider the following system of linear equations:
x + 3y + 3z = a
2x + 5y + 4z = b
2x + 7y + 8z = C
Which, if any, of the following statements is true?
a None of the given answers is correct.
.
b. The linear system has a unique solution if 2a + c = 0.
c.
The linear system has no solution if b + c > 4a.
d. The linear system has a unique solution if – 2a + b + c = 0
The linear system has an infinite number of solutions if b + c = 4a.
Of. The linear system has no solution if b + c < 4a .