设f(0)的二阶导数存在,且f(0)=0,g(x)=f(x)/x (x≠0时) g(x)=f(0)的导数(x=0时),则g(0)的导数为x=0时,g'(0) = lim(x→0) [g(x)-g(0)]/(x-0)=lim(x→0) [f(x)/x-f'(0)]/x=lim(x→0) [f(x)-xf'(0)]/x²=lim(x→0) [f'(x)-f'(0)]/
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设f(0)的二阶导数存在,且f(0)=0,g(x)=f(x)/x (x≠0时) g(x)=f(0)的导数(x=0时),则g(0)的导数为x=0时,g'(0) = lim(x→0) [g(x)-g(0)]/(x-0)=lim(x→0) [f(x)/x-f'(0)]/x=lim(x→0) [f(x)-xf'(0)]/x²=lim(x→0) [f'(x)-f'(0)]/
设f(0)的二阶导数存在,且f(0)=0,g(x)=f(x)/x (x≠0时) g(x)=f(0)的导数(x=0时),则g(0)的导数为
x=0时,g'(0) = lim(x→0) [g(x)-g(0)]/(x-0)=lim(x→0) [f(x)/x-f'(0)]/x=lim(x→0) [f(x)-xf'(0)]/x²=lim(x→0) [f'(x)-f'(0)]/(2x)=(1/2)f''(0) 这个罗比达法则是怎么用的?最后两步跟我做的不一样
设f(0)的二阶导数存在,且f(0)=0,g(x)=f(x)/x (x≠0时) g(x)=f(0)的导数(x=0时),则g(0)的导数为x=0时,g'(0) = lim(x→0) [g(x)-g(0)]/(x-0)=lim(x→0) [f(x)/x-f'(0)]/x=lim(x→0) [f(x)-xf'(0)]/x²=lim(x→0) [f'(x)-f'(0)]/
g(0)=f'(0)
按照定义 g'(0)=lim(x->0)[g(x)-g(0)]/[x-0]
=lim(x->0)[f(x)/x-f'(0)]/x
=lim(x->0)[f(x)-xf'(0)]/x²
当x趋向于0时 f(x)->f(0)=0
xf'(x)->0
x->0
所以运用罗比他法则
上下同时求导
g'(0)= lim(x→0) [f'(x)-f'(0)]/(2x)
因为此时当x趋向于0时 f'(x)-f'(0)->0
所以再一次罗比他法则
得 g'(0)= lim(x→0) [f'‘(x)]/2
=(1/2)f''(0)
f(0) =0
g(x) = f(x)/x ; x ≠0
= f'(0) ; x=0
g'(0) = lim(h->0)[ g(h) - g(0)] / h
=lim(h->0) [ f(h)/h - f'(0)...
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f(0) =0
g(x) = f(x)/x ; x ≠0
= f'(0) ; x=0
g'(0) = lim(h->0)[ g(h) - g(0)] / h
=lim(h->0) [ f(h)/h - f'(0) ]/h
=lim(h->0) [ f(h) - hf'(0) ]/h^2 (0/0) 分子 f(0) -0.f'(0) =0, 分母=0: 分子,分母分别取导数
=lim(h->0) [ f'(h) - f'(0) ]/(2h) (0/0) 分子 f'(0) -f'(0) =0, 分母=0: 分子,分母分别取导数
=lim(h->0) f''(h)/2
=f''(0)/2
收起