- How did Jane get the job so easily? - She_______ speak French very well. A. should B. shall C. may D. could 答案:D(2012•香洲区模拟)定义函数fn(x)=(1+x)n-1,x>-2,n∈N(1)求f3(x)的极值点;(1)求证:fn(x)≥nx;(2)是否存在区间[a,0](a<0),使函数h(x)=f3(x)-f2(x)在区间[a,0]上的值域为[k-a,0]?若存在,求出最小的k值及相应的区间[a,0],若不存在,说明理由.