已知函数f(x)=x+1(x ≤ 0)且logx(x>0),则函数y=f[f(x)]+1的零点个数是______.f(x)是分段函数,对数的底为2.

已知函数f(x)=x+1(x ≤ 0)且logx(x>0),则函数y=f[f(x)]+1的零点个数是______.f(x)是分段函数,对数的底为2.
已知函数f(x)=x+1(x ≤ 0)且logx(x>0),则函数y=f[f(x)]+1的零点个数是______.
f(x)是分段函数,对数的底为2.

已知函数f(x)=x+1(x ≤ 0)且logx(x>0),则函数y=f[f(x)]+1的零点个数是______.f(x)是分段函数,对数的底为2.
分四种情况讨论,x≤-1,-1