Finding centroid of region bounded by y=x, y=3x, x=n

[kiwwi]

Homework Statement

Find the centroid (center of mass) of the region in the first quadrant bounded by y=x, y=3x, x=n (>0)

Homework Equations

The Attempt at a Solution

No idea how to start the question, since I have to get the area of the region but
the graph does not intersect the second time. So it would be an area to inifinity.

 

[SammyS]

There are three lines.

 

[Dick]

The x boundaries of the region are x=0 and x=n, aren't they? There's a third curve x=n. Both lines hit it. You can make a better start than that.