Hey guys i need some help before my exam, which is in 2 days

1.) f(x) = log2 (x-4)

When graphing the function i got the domain to be (4,infinity) and the range to be (-infinity, infinity) but the book shows the answer to be: Domain: R with a little + sign and range as R. Please explain.

Sorry but i have a few more questions to ask:

1.) Use a graphics calculator to plot the graphs of y= log10 (x^2) and y = 2 log10 x for x =[-10,10].

i don't understand how they say x = [-10,10] when the asymptote is at x = 0? how can it be inclusive of -10 when it never goes beyond x = 0?