Hello,

Resolving power of an instrument is the ability to distinguish  clearly between two points which  are located at a small angular distance .

Resolving power=D/1.22*lambda

D is the diameter of aperture.

As you can see RP is inverserly proportional to wavelenght used and directly proportional to diameter of lens.Hence when wavelenght increases RP decreases and when D increases RP increases.

You can see the link for understanding the topic

https://school.careers360.com/ncert/ncert-solutions-class-12-physics-chapter-9-ray-optics-and-optical-instruments

Hope it helped.