Let `C` be the curve ` y = 6 sqrt( x ) ` for `1.9 le x le 3.1`.
Graphing window shows horizontal axis: 1 to 4, vertical axis: 0 to 12. Dot at (1.9,8.2704292512541), color blue. Dot at (3.1,10.564090116995), color blue. Start Graph, Color black

x	y
1	6
2	8.485
3	10.392
4	12

Find the surface area of revolution about the `x`-axis of `C`.

Surface area `= int_1.9^3.1 f( x ) \ dx` where
`f( x ) =`  
Now integrate to find surface area `= int_1.9^3.1 f( x ) \ dx =`