calculus pleas pleas help, derivates
posted by david .
what is the derivative of x/tan(x) and find f'(pi/4)
f'(x)=(tanxx*sec(x)^2)/(tanx)^2
That's the quotient rule for derivatives or as my teacher says:
Low,low, low D'High, minus High d'low all over low square that's the quotient rule. It's a song which helps. D'High or d'low means the derivative of the top or bottom.
Anyways: the answer choices are:
2,1/2,1+pi/2,pi/21, 1pi/2
and i keep getting 1pi/8. This question is from an AP test in 1985 so i don't think they made a mistake in these answers.
deriv = (1*tan x  x sec^2 x)/tan^2 x
so for x= pi/4
deriv = (1  pi/4(2))/1
=1  pi/2, which was one of the choices
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