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What is the frequency of the function f(x)?

 

f(x) = 1/4 cos (2x) + 5

 

Express the answer in fraction form.

 Jan 24, 2020
 #1
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+1

f(x) = 1/4 cos (2x) + 5

 

Only one of these numbers will affect frequency.  Which one is it?

 

Answer this question and then I, or someone else will continue

 

This is a teaching answer, please no one else answer over me.

 

Hint, here is the graph.

 
 Jan 24, 2020
 #2
avatar+151 
+1

To be entirely honest, I'm not sure how these concepts work. The material my teacher gives me seems to go straight over my head, and with a general lack of enthusiasm for mathematics, I struggle to make sense of how it works on my own.

 
 Jan 24, 2020
 #3
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I can try and help you but you will have to cooperate.

 

First you must know that 360 degrees is the same as   2pi  radians.

This type of trig is nearly always done in radians.

 

 

Ok here is the 'parent' function.

 

y= cos x

 

For this parent funtion please tell me what tthese are

a) The midline

b) the frequency (how far does it go before the patern repeats)

c) The amplitde  (How far above the middle is the top)

 

 
 Jan 24, 2020
 #4
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+1

I apologize, I struggle with even the very basics of what some of these questions ask.

I'm not very confident in mathematics, which I doubt helps my struggles. 

 

I assume the midline is (0, 1), and I assume the amplitude is (pi, -1).

 

I'm not really sure how to to determine frequency? Is it (2pi, 1)?

 
 Jan 24, 2020
edited by PeerlessCucumber  Jan 24, 2020
 #5
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+1

ok thanks for answering.

 

y=cos x

The midline is the x axis.  Can you see that .. it is the middle of the graph?

 

The x axis is a line and it has an equation.

Can you see that  (0,0),   (pi,0),   (7pi/4, 0)   etc are all on this x axis?  What do all these points have in common?

Hint: What is the y value?

 

 

 

 

 
Melody  Jan 24, 2020
 #6
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+1

Lets go further back.

My questions may seem off topic to you but they are not. 

Most likely you will understand easily if you get some basics first.

 

What is the equation of this line.

 

 
 Jan 24, 2020
 #7
avatar+107414 
+1

Can you see that the y value is always 3 so the answer is y=3  

--------------------

 

How about this one ...   what is the equation?

 

 
Melody  Jan 24, 2020
 #8
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+1

Then in this case, y = 2?

 
PeerlessCucumber  Jan 27, 2020
 #9
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Yes that is correct.    laugh

Using the same logic, what is the equation of the x axis ?

 
Melody  Jan 27, 2020
edited by Melody  Jan 27, 2020
 #10
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I suppose it could be many different points, such as (1, 3) or (2, 3)?

 
PeerlessCucumber  Jan 27, 2020
 #11
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ok, try this.

 

Here I have graphed the x axis and I have put 5 points on it.

I would like you to tell me what those points are.

 

Like I want    A(?,?)    you fill in the question marks.

 

After that I want you to tell me what all the points have in common.

And then, if you can tell me what the equation of the line is.  

 

 
Melody  Jan 27, 2020
 #12
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A = (-4, 0)

 

B = (0, 0)

 

C = (1, 0)

D = (3, 0)

 

E = (10, 0)

Are these correct? If so, I'm notice they're all on the same line, their Y is ultimately 0.

 
PeerlessCucumber  Jan 28, 2020
 #13
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Yes everythign you just said is correct.

So what is the equation of the line do you think.  (Look at the last examples if you are still confused)

 
Melody  Jan 28, 2020
edited by Melody  Jan 28, 2020
 #14
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I had another question for you here too.

https://web2.0calc.com/questions/which-function-is-shown-on-the-graph#r4

Calc

https://www.desmos.com/calculator

 

It will help a lot if you learn to use the graphing calc.  It is easy to use. If you need help then explain why.

This is what I asked you to graph

B. f(x)=1/2 cos x  

 

Put it in as       y=1/2*cosx

Answer on the original thread.

 
 Jan 28, 2020
 #15
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I answered.

 
PeerlessCucumber  Jan 28, 2020
 #16
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No you didn't answer my most recent question yet.

I asked you for a link to your graph that you said you drew.

 

 

You have not yet answered my last question on this thread either.  I asked you for the equation of the x axis.  It was #13 on this thread.

 
Melody  Jan 28, 2020
edited by Melody  Jan 28, 2020
 #17
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Ok I see your answer now, I have commented and asked another question.  Thanks. :) 

 
Melody  Jan 28, 2020

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