Help Plz

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Xeris

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Jul 19, 2005
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Can anyone help me with this problem I just cant seem to figure it out. Its been to long since Ive done this stuff.

Find f(n^r/4) if f( X) = (-2 sin (2X))/3 + (5 cos (4X))/6

Thanks.
 
Xeris said:
Find f(n^r/4) if f( X) = (-2 sin (2X))/3 + (5 cos (4X))/6
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First, just plug it in. That's what the notation means.

If f(x) = (-2 sin (2x))/3 + (5 cos (4x))/6, then
f(n^r/4) = (-2 sin (2(n^r/4)))/3 + (5 cos (4(n^r/4)))/6

Simplify that as you wish.
 
how would you simplify it? Thats the part that in stuck on. It has to break down to -3/2 and thats what I cant seem to get.
 
First, I'm not sure what you mean by n^r/4.

Is that

n^(r/4)

or

(n^r)/4

Feel free to use parentheses to clarify your meaning.
 
You sure are you of that argument?

Your f(X) achieves -3/2 at pi/4 + k*pi, for k an Integer.

I'm really not seeing how ¼n<sup>r</sup> does that.
 
Maybe it was the othre way. I must have just interpreted it wrong. But the way that I wrote it down was the exact way they gave it to me.
 
Well, when you find the solution, be sure to let us know.

Are you sure that 'n' is really an 'n', or is it a 'pi'-symbol?
 
It was an "n" but maybe they ment to put a pi sign. If it was a pi sign would it be able to reduce to -3/2?
 
Not a clue. I was hoping n = pi was just a sign that there were other things wrong with the problem statement.

I appeal to the masses for additional ideas. I'm fresh out.
 
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