Now you are asking a different question! We are talking big fans. RR did not have the resources the other companies had and it went for a more technically complicated solution (3 spools). The Tristar did not sell as well as the DC10 as it did not already have a captive market of DC8 type aeroplane operators and it's range was inadequate. It seems to have been a better short/medium range high capacity aeroplane than the DC10, though not matching the 10 for long range. To get LHR-LAX, it had to be made in a shrunk version, and even then it was no good for that whilst the DC10 was happily flying the route.
The Rolls Royce RB211 went on to become a very efficient and reliable engine powering all Tristars and BA 747s, 767s and even 757s (I think it may even power half or more of all 757s). Derivatives are now powering the A380/777, so there was nothing 'difficult' about the Tristar engine, just a slightly more protracted development.
Now your turn! What are these questions about and why?