Question

高数求导，

如图，为啥我做错了?

Answer 1

你方法有误

追答

Answer 2

x=a(t-sint)

dx/dt = a(1-cost)

y=a(1-cost)

dy/dt = asint

dy/dx = (dy/dt)/(dx/dt) =sint/(1-cost)

d/dt (dy/dx) 

= [(1-cost)cost -sint.(sint) ] /(1-cost)^2

= (cost -1)/(1-cost)^2

= -1/(1-cost)

d^2y/dx^2

=[d/dt (dy/dx) ]/ (dx/dt)

=[ -1/(1-cost)] /[ a(1-cost)]

=-1/[a(1-cost)^2]

Answer 3

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