x=f'(t)且y=tf'(t)-f(t)设-查字典问答网
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  x=f'(t)且y=tf'(t)-f(t)设f''(x)存在且不为零.求f''(x)

  x=f'(t)且y=tf'(t)-f(t)设f''(x)存在且不为零.求f''(x)

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2020-07-2909:32
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汪审权

  x=f'(t)

  y=tf'(t)-f(t)

  dy/dx

  =[dy/dt]/[dx/dt]

  =[f'(t)+tf''(t)-f'(t)]/f''(t)

  =t

  d^2y/dx^2

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

  =1/f''(t)

  f''(x)=1/f''(t)

2020-07-29 09:37:15
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