考研数学 导数定义问题~
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考研数学 导数定义问题~
![考研数学 导数定义问题~](/uploads/image/z/19945900-28-0.jpg?t=%E8%80%83%E7%A0%94%E6%95%B0%E5%AD%A6+%E5%AF%BC%E6%95%B0%E5%AE%9A%E4%B9%89%E9%97%AE%E9%A2%98%7E)
A = lim[sin3x/x^3+f(x)/x^2] = lim[sin3x-xf(x)]/x^3 = 0 (0/0)
则 A = lim[3cos3x-f(x)-xf'(x)]/(3x^2) = 0,则 f(0)=3,(0/0)
A = lim[-9sin3x-2f'(x)-xf''(x)]/(6x) = 0,则 f'(0)=0,(0/0)
A = lim[-27cos3x-3f''(x)-xf'''(x)]/6 = 0,则 f''(0)=-9,
则 A = lim[3cos3x-f(x)-xf'(x)]/(3x^2) = 0,则 f(0)=3,(0/0)
A = lim[-9sin3x-2f'(x)-xf''(x)]/(6x) = 0,则 f'(0)=0,(0/0)
A = lim[-27cos3x-3f''(x)-xf'''(x)]/6 = 0,则 f''(0)=-9,