設函數f(x)=x(x-a)的平方在x=2處有極大值,求實數a的值.

設函數f(x)=x(x-a)的平方在x=2處有極大值,求實數a的值.

f(x)= x(x - a)= x^2 - ax =(x - a/2)^2 - a^2/4當x = a/2時,f(x)有極小值.所以x = a/2 = 2 ==> a =4.min[f(x)] = -a^2/4 = -4^2 / 4 = - 4