題目:設(shè)函數(shù)f(x)在[a,b]上連續(xù),在(a,b)內(nèi)可導(dǎo),且f(a)=f(b)=0,f(2a+b?)>0,則根據(jù)介值定理,存在c∈(a,b),使得( )。A. f(c)=0B. f′(c)=0C. f(c)=f(a)D. f(c)=f(2a+b?)