Here, coefficient of x2 = 6, coefficient of x = -5y and constant term = - 6y2
We shall now split up the coefficient of middle term i.e., -5y into two parts whose sum is -5y and product is 6 (-6y2) = - 36y2
Clearly,
4y – 9y = -5y and
(4y) (-9y) = - 36y2
So, we replace middle term -5xy = 4xy – 9xy
Thus, we have
6x2 -5xy- 6y2 = 6x2 + 4xy - 9xy - 6y2
= (2x – 3y) (3x + 2y)