Kendall says the sum of (6x^2+4xy+2y^2) and (4x^2-2xy-3y^2) is (10x^2+2xy-5y^2) what error did kendall make

(6x^2 + 4xy + 2y^2) + (4x^2 - 2xy - 3y^2)
=
(10x^2 + 4xy - y^2)

Kendall assumed the 2y^2 was negative and not positive leading her to create the error of -5y^2

Hope this helps :)

The operation is suck a c@ck? !