设偶函数y=f(x)满足f(x)=x²-8(x≥0)则{x丨f(x-2)>0}等于?我想要下过程,

问题描述:

设偶函数y=f(x)满足f(x)=x²-8(x≥0)则{x丨f(x-2)>0}等于?我想要下过程,

f(x)=x²-8(x≥0),f(x-2)=(x-2)²-8,x≥2;
f(x-2)=(x-2)²-8=x²-4x-4>0,得x2+根号2,
又因为定义域要求x≥2,则结果为x>*根号2+2