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calculus 1 hw problem!?
i have noooo idea how to do this, there must be some trick to do it, i appreciate any help
thanks in advance!
Find the 85th derivative of y = cos(3x).
the first derivative of y = cos(3x)
y' = -sin(3x) * 3
= -3 sin(3x)
i'm absolutely sure of that one...
3 Answers
- santmann2002Lv 71 decade agoFavorite Answer
y´=-3sin3x
y´´=-3^2 cos3x
y´´´= 3^3 sinx
y´´´´= 3^4 cos3x
so after four steps you return to cos 3x multiplied by 3^4
so as84 is a multiple of 4
y(84) = 3^84 cos 3x and
y(85) = -3^85sin3x
- 1 decade ago
I'm going to assume that you can derive y = cos(3x) regularly.
y' = -9^1 cos(3x)
y'' = 9^2 cos(3x)
y'''= -9^3 cos(3x)
y''''= 9^4 cos(3x)
etc.
From that pattern, you can determine that
y to the nth prime = (-9)^n cos(3x)
so y to the 85th prime = (-9)^85 cos(3x)
- stinnetteLv 45 years ago
ln(2^n) = n * ln(2), so that you've this sequence: ? a million / ln(2^n) = ? a million / (n * ln(2)) = (a million / ln(2)) * ? a million/n. because the quotient (a million / ln(2)) is only a authentic volume, your sequence converges if (and on condition that) ? a million/n does. besides the undeniable fact that it would not converge, and so neither does your sequence.