решить систему уравнений х+у=2 ху=-15

Y = 2 - X 
X * ( 2 - X ) = - 15 
2X - X^2 = - 15 
X^2 - 2X - 15 = 0
D = 4 + 60 = 64 ; √ D = 8 
X1 = ( 2 + 8 ) : 2 = 5 
X2 = ( 2 - 8 ) : 2 = - 3 
Y1 = 2 - X1 = 2 - 5 = - 3 
Y2 = 2 - x2 = 2 + 3 = 5