Find all real solutions to the following system of nonlinear
Find all real solutions to the following system of non-linear equations:
x2+xy+y2=3
x2-3xy+y2=11
Solution
given
x^2+xy+y^2=3 -------->1st
x^2-3xy+y^2=11 --------->2nd
in the 1st equation take \'xy to the right hand side
then we get x^2 +y^2 = 3 -xy
plug x^2+y^2 value in equation 2
then we get
3 - xy -3xy =11
3 -4xy =11
-4xy =11-3
-4xy =8
xy =-2
y = -2/x
plug this \'y\' value in equation1
x^2 -x (2/x) +(4/x^2) =3
x^4 -2x^2 +4= 3x^2
x^4 -5x^2 +4=0
x= 1,-1 satisfy this
x^4 -5x^2 +4 can be wrriten as (x^2 -1) (x^2 -4)
so (x^2 -1) (x^2 -4) =0
x = 1, -1 ,2,-2
now find put y value by y = -2/x
when x=1 y =-2 solution is (1,-2)
when x=-1 y =2 sloution is (-1,2)
when x=2 y =-1 solution is (2,-1)
when x=-2 y=1 solution is(-2,1)
