Let f be the function given by f(x)= 2x/sqrt(x^2 + x + 1)

A) find the domain and justify

B) write an equation for each horizontal asymptote

C) does the graph cross any horizontal asymototes? Show work

So I started this and got

A) domain is all reals because denominator doesn't have restrictions

B) y=2 and y=-2 however I found these graphically and need to know how to do that algebraically

C) yes it crosses y=-2 (I also found this graphically and need it algebraically)

Thanks so much in advance!!!