※ 引述《googoodoll (浮沉隨浪．志氣高)》之銘言：
: lim ln(cos(2πx))/x^2 = ?
: x→0
: thanks :D
ln(cos(2πx))
lim ---------------
x→0 x^2
((2π)(-1)(sin(2πx))/(cos(2πx))
= lim -----------------------------------
x→0 2x
sin(2πx) 1
= (-1)(2π)(lim -----------)(lim -----------)
x→0 2x x→0 cos(2πx)
sin(2πx) 1
= (-2π)(π)(lim -----------)(---)
x→0 2πx 1
= (-2)(π^2)(1) = (-2)(π^2)
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