函数y=根号下log10(x^2-x-1)的定义域是?

来源:学生作业学帮网 编辑:学帮网 时间:2024/05/17 01:24:57

函数y=根号下log10(x^2-x-1)的定义域是?

y=根号下log10(x^2-x-1)的定义域是
log10(x^2-x-1)>=0
真数:x^2-x-1>0
log10(x^2-x-1)>=0
x^2-x-1>=1
(x-2)(x+1)>=0
x>=2,x0
(x-1/2)^2>5/4
x>1/2+根号5/2,X

由题意,log10(x^2-x-1)>=0,所以x^2-x-1>=1恒大于0,即x>=2或x<=-1即为所求