Find Lim [x tends to infinity] {(x ^ 3) * ln [(x + 1) / (x-1)] - 2x ^ 2}, the answer is 2 / 3,

Find Lim [x tends to infinity] {(x ^ 3) * ln [(x + 1) / (x-1)] - 2x ^ 2}, the answer is 2 / 3,

Lim [x tends to infinity] {(x ^ 3) * ln [(x + 1) / (x-1)] - 2x ^ 2}
=Lim [x tends to infinity] {(x ^ 2) {XLN [(x + 1) / (x-1)] - 2}
=Lim [x tends to infinity] {XLN [1 + 2 / (x-1)] - 2} / [x ^ (- 2)]
=Lim [x tends to infinity] {ln [1 + 2 / (x-1)] + x [1 + 2 / (x-1)] ^ (- 1) [- 2 / (x-1) ^ 2]} / [- 2x ^ (- 3)]
=Lim [x tends to infinity] {- 2x / (x-1) ^ 2 [- 2x ^ (- 3)]
=2/3