Please help me with this problem

A function is said to have a horizontal asymptote if either the limit at infinity exists or the limit at negative infinity exists. Show that each of the following functions has a horizontal asymptote by calculating the given limit. -4x lim 15 + 2x 14x - 15 lim 4-00 23+13x -7 x2 - 2x - 5 lim 11 x-+00 7 - 12x2 Vx2 + 6x lim 4- 3x Vx2 + 6x lim 4 - 3x