你好:此题应选A解:f(x)'=anx^(n-1)×(1-x)²+axⁿ×2(1-x)×(-1) =ax^(n-1)[(n+2)x²-2(n+1)x+n] =a(n+2)x^(n-1)[x-n/(n+2)][x-1]∵n/(n+2)=1-2/(n+2)<1显然当00 当n/(n+2) ∴f(x)在x=n/(n+2)处有极大值。也是最大值 ∵在图中最大值在0.3到0.4之间∴n/(n+2)属于(0.3,0.4)将选项代入可知,n=1符合题意