Ответы и объяснения

2013-07-02T20:27:25+00:00
  • AlbuRin
  • светило науки
2013-07-03T01:33:40+00:00

{x^2 +y^2 = 25    {x^2  -24 + y^2 = 1  ----> x^2 +2xy +y^2 = 1 ----->   {(x+y)^2 =1

{xy = -12              {2xy = -24                                                                    {xy  =  -12

 

1) случай   {x+y=1     {x=1-y                                                                           х_1 = -3   х_2 = 4  

                     {xy=-12   {(1-y)y=-12 ----> y^2-y-12=0 По теореме Виета у_1 = 4   у_2 = -3

 

2) случай   {x+y=-1     {x=-y-1                                                                           х_3 = 3    х_4 = -4

                     {xy=-12    {(-y-1)y=-12 ---->y^2+y-12=0  Потеореме  Виета  у_3 =-4   у_4 = 3