Answer:

Step-by-step explanation:
<u>Equation of a Polynomial</u>
Given the roots x1, x2, and x3 of a cubic polynomial, the equation can be written as:

Where a is the leading coefficient.
We know the three roots of the polynomial -6, -3, and 1, thus:

Since the y-intercept of the polynomial is y=90 when x=0:
90=a(0+6)(0+3)(0-1)
90=a(6)(3)(-1)=-18a
Thus
a = 90/(-18) = -5
The polynomial is:

We must write it in standard form, so we have to multiply all of the factors as follows:





The answer is going to be
X=20
Using Pythagorean theorem, the answer should be 8.7ft
Answer: A) 
B) H = 5.10
C) Yes
Step-by-step explanation: <u>Exponential</u> <u>Decay</u> <u>function</u> is a model that describes the reducing of an amount by a constant rate over time. Generally, it is written in the form: 
A) C is initial quantity, in this case, the initial concentration of DDT. To determine r, using the data given:



Using a natural logarithm property called <em>power rule:</em>



The decay function for concentration of DDT through the years is 
B) The value of H is calculated by 


Again, using power rule for logarithm:



H = 5.10
Constant H in the half-life formula is H=5.10
C) Using model
to determine concentration of DDT in 1995:

y(24) = 0.5
By 1995, the concentration of DDT is 0.5 ppm, so using this model is possible to reduce such amount and more of DDT.