Answer:
c.
Step-by-step explanation:
All of the things are correct with this one.
Answer:
5.59 times per second.
Step-by-step explanation:
Direct variation is in the form:

Where <em>k</em> is the constant of variation.
Inverse variation is in the form:

In the given problem, the frequency of a vibrating guitar string varies inversely as its length. In other words, using <em>f</em> for frequency and <em>l</em> for length:

We can solve for the constant of variation. We know that the frequency <em>f</em> is 4.3 when the length is 0.65 meters long. Thus:

Solve for <em>k: </em>
<em />
<em />
<em />
So, our equation becomes:

Then when the length is 0.5 meters, the frequency will be:

3/(5/4) = x/1
x = 12/5 = 2.4 Problems/h
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
Is the answer to your question 9?