The answer is C because x2 is a parabola
Answer:

Step-by-step explanation:
Given
--- Amplitude
--- Right phase shift
Required
Identify the function
A sinusoidal function is defined as:

Substitute values for A and C

By comparison, only option (D) has the above format where

Hence (D) is correct
For sake of convenience, reverse the series, then it would be:
21,19,17.....7
a=21, d = -2,
s(4) = 4/2 (21+15)
s(4)=2(36)
s(4) = 72
Answer:
The common ratio is 4
Step-by-step explanation:
We need to divide a term by the previous term to find the common ratio in a geometric sequence:
64 ÷ 16 = 4
256 ÷ 64 = 4
By doing it twice we can confirm that the common ratio is 4
The area of the cross-section is 169 sq. cm.
That is the correct answer to this problem