x2+2xy+y2-9xy+6x2=7x2-7xy+y2 after expanding parentheses.
y2-7xy+7x2 can be factorised with irrational factors:
(y2-7xy+49x2/4)+(7-49/4)x2=
(y-7x/2)2-21x2/4, difference of two squares:
(y-7x/2+x√21/2)(y-7x/2-x√21/2),
(y-½x(7-√21))(y-½x(7+√21)),
(y-1.2087x)(y-5.7913x) approx.