Alfred_F

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These are questions asked by Alfred_F

In the attached file, (6) is stated as "false." However, it is possible to prove with pen and paper that term1 = term2. In (5), the limit function is sought but not determined.
What am I doing wrong?test1.mw
 

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term1 := (2*cos(2^n*x)+1)/(2*cos(x)+1)

(2*cos(2^n*x)+1)/(2*cos(x)+1)

(1)

term2 := product(2*cos(2^k*x)-1, k = 0 .. n-1)

product(2*cos(2^k*x)-1, k = 0 .. n-1)

(2)

term3 := term1*(2*cos(2^n*x)-1)/(2*cos(x)-1)

(2*cos(2^n*x)+1)*(2*cos(2^n*x)-1)/((2*cos(x)+1)*(2*cos(x)-1))

(3)

simplify(term3)

(1+2*cos(2^(1+n)*x))/(1+2*cos(2*x))

(4)

limit((1+2*cos(2^(1+n)*x))/(1+2*cos(2*x)), n = infinity)

limit((1+2*cos(2^(1+n)*x))/(1+2*cos(2*x)), n = infinity)

(5)

is(term1 = term2)

false

(6)

NULL


 

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In the attached file, I would like to determine the real part of the complex term2. I'm asking for your help.test.mw

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term1 := exp(I*t/2^k)

exp(I*t/2^k)

(1)

term2 := product(term1, k = 1 .. n)

(cos(2*t*(1/2)^(n+1))-I*sin(2*t*(1/2)^(n+1)))/(cos(t)-I*sin(t))

(2)

``

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On my journey of discovery through the world of Maple, I would like to ask for help again:
How are the properties of variables and the indexing of sequences handled/determined? For this purpose, I chose an old problem from a challenging MO as an exercise and tried it in the attached file, which, of course, failed.

restart

a[i] := 2*cos(t/2^i)-1

2*cos(t/2^i)-1

(1)

b[n] := product(a[i], i = 1 .. n)

product(2*cos(t/2^i)-1, i = 1 .. n)

(2)

limit(b[n], n = infinity)

limit(product(2*cos(t/2^i)-1, i = 1 .. n), n = infinity)

(3)

simplify(limit(b[n], n = infinity))

limit(product(2*cos(t*2^(-i))-1, i = 1 .. n), n = infinity)

(4)

NULL

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The attached problem is from a 1988 MO. It can be solved using complete induction, paper, and pencil, and with some effort, yields a simple answer. It's quite challenging to do by hand, but with "derive", it only takes three lines and a fraction of a second. Mow test.mw

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"puzzle(n):=(∑)(cos(k*Pi/(2*n+1))^())^(4);"

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I can't do it with Maple because I'm doing something wrong again. Therefore, I'm asking for help.

When calculating limits of real-valued functions, sometimes (especially in competitions) tricky approaches are taken using pen and paper. I repeatedly encountered the simple conclusion that, for example, for natural k, the value sin(k*pi) = 0. Thus, the function value is determined logically without specifying a specific number. There are numerous other examples of this that can easily be constructed.
My question after unsuccessful attempts using "assume" is:
How, for example, does Maple determine the value of sin(k*pi) from the assumption "k is natural" alone? Are such prominent values ​​implemented in tables?

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