 yokofoku 
                                                05.05.2021 16:26
                                                
                                                yokofoku 
                                                05.05.2021 16:26
                                             tasyakondrateva0 
                                                05.05.2021 16:27
                                                
                                                tasyakondrateva0 
                                                05.05.2021 16:27
                                             OшUb0чkA 
                                                05.05.2021 16:27
                                                
                                                OшUb0чkA 
                                                05.05.2021 16:27
                                             Dashalu45 
                                                05.05.2021 16:28
                                                
                                                Dashalu45 
                                                05.05.2021 16:28
                                             zippops 
                                                05.05.2021 16:28
                                                
                                                zippops 
                                                05.05.2021 16:28
                                             Maksim77769 
                                                05.05.2021 16:28
                                                
                                                Maksim77769 
                                                05.05.2021 16:28
                                             star1k 
                                                05.05.2021 16:29
                                                
                                                star1k 
                                                05.05.2021 16:29
                                            
D = 9 + 20 = 29
x1 = (3-√29)/2
x2 = (3+√29)/2
1) 1/x1 + 1/x2 = 2/(3-√29) + 2/(3+√29) = (6+2√29+6-2√29)/(9-29) = 12/(-20) = -3/5 = -0,6
2) x1² + x2² = (3-√29)² + (3+√29)² = 9 -6√29 + 29 + 9 + 6√29 + 29 = 76
3) x1/x2 + x2/x1 = (x1² + x2²)/(x1*x2) = 76/((3-√29)(3+√29)) = 76/(9-29) = 76/(-20) = -19/5 = -3,8