How to express this result in decimals ?

 This is tha problem;

 phi_dash=
  (4610380494485263574757718612977234468314401*lm)/7922816251426433759354395033600000000 + (1019951*(lm/50 - 1/10)*((1019951*lm)/5000 - 1/10))/250000 + 39557066627230955162521978564721796741737/316912650057057350374175801344000000

now I solve phi_dash for the value of lm :

lm = 
 - (5*332015728275546103153905076369467549472288547520028183859860526409371981428693266764066121^(1/2))/164842121645885018331771899676795676393472 - 2881075663344753229384532006925206708928748945/164842121645885018331771899676795676393472
   (5*332015728275546103153905076369467549472288547520028183859860526409371981428693266764066121^(1/2))/164842121645885018331771899676795676393472 - 2881075663344753229384532006925206708928748945/164842121645885018331771899676795676393472

Answer 1

[Star Strider]

Use the vpa (link) or double (link) functions.