证明：f(x)=2x^3-6x^2+7 f'(x)=6x^2-12x =6x(x-2) 当0 所以，f(x)在(0,2)上是减函数
f(x)=2x^3-6x^2+7f'(x) = 6x^2 - 12x = 6x(x-2)for x∈(0,2)f'(x) >0=> f(x)=2x^3-6x^2+7在(0.2)内是减函数
证明：∵f'(x)=6x²-12x=6x(x-2)∴0∴函数f(x)=2x^3-6x²+7在(0,2)内是减函数证毕
