give the domain, range, and zeros of:

Question

f(x)=absoulte value of x-3.
f(x)=x^2-4x-8
f(x)=(x+1)(x+1)(x+1).
f(x)=4
f(x)=-'9x-1)^2+16
y=squareroot x.

i don't understand how i konw what the range, domain, and zeros are...please give some answers so i get it