※ 引述《JULIKEBEN (JU)》之銘言：
: let f: R→R be twice differentiable .
: if f'' is nowhere vanishing , then f has at most two distinct real roots.
we given f have three roots x1,x2,x3 let x1>x2>x3
and then we know f(x1)=f(x2)=(x3)
so according to Roll's T.H.M. know
have c1 on ( x1,x2) ,c2 on(x2,x3> let f'(x1)=0 ,f'(x2)=0
because f'(x1)=f'(x2)=0 and according to Roll's T.H.M
have c3 on <x1,x2> let f''(c3)=0 but f'' is nowhere vanishing
so f only have two distinct
: 請問高手
: 這題該如何解??
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