Giải thích các bước giải:
a) `2x^2-3xy-6y^2`
`=(2x^2-(3+sqrt57)/2xy)+((-3+sqrt57)/2xy-6y^2)`
`=2x(x-(3+sqrt57)/4y)+(-3+sqrt57)/2y(x-(3+sqrt57)/4y^2)`
`=2x(x-(3+sqrt57)/4y)-(3-sqrt57)/2y(x-(3+sqrt57)/4y^2)`
`=(2x-(3-sqrt57)/2x)(x-(3+sqrt57)/4y)`
b) `3x^2 + 5xy + 2y^2 − 4x − 4y `
`= ( 3 x ^2 + 3 x y ) + ( 2 x y + 2 y ^2 ) − ( 4 x + 4 y ) `
`= 3 x ( x + y ) + 2 y ( x + y ) − 4 ( x + y ) `
`= ( 3 x + 2 y − 4 ) ( x + y )`
