Plot3D[(27/(x y)) + x + y, {x,  .2, 10}, {y,  .2, 10}, 
      PlotPoints -> 50, PlotRange -> {0, 25}, 
      ClipFill -> None, BoxRatios -> {1, 1, 1}]

Plot3D[((x^2)) (((y + 2))^3) + (y^2), {x, -6, 6}, {y, -3, 
        3}, PlotPoints -> 50, PlotRange -> {-10, 10}, 
      ClipFill -> None, BoxRatios -> {1, 1, 1}]