By definition we have to:
A set has under an operation if performance of that operation on set members always produces a member of the same set; in this case we also say that the set is closed under the operation.
For this case we have the following polynomials:

Multiplying we have:

The product of two polynomials is also a polynomial.
Answer:
d
is a polynomial
Answer:
90
Step-by-step explanation:
To find s4 we find sum of values when n=1,n=2,n=3,n=4
given expression is 
n=1 , plug in 1 for n

n=2

n=3

n=4

Sum of all 4 terms = 6+12+24+48=90
Multiply each exponent inside the parentheses by the exponent on the outside:
8^(-5 x -4) / 2^(-2 x -4)
8^20 / 2^8
The answer is C
<span>Equation F can be written as 2d + 1 = 3d + 7.</span>
Answer:69.15
Step-by-step explanation: the deviation is 6 which and 1/6 of people got the same grade as him - 100 = 69.15