3x^4y^2+3x^3y^2+3xy^2+3y^2
=( 3x^4y^2 + 3x^3y^2 ) + ( 3xy^2 + 3y^2 )
= 3x^3y^2 . (x+1) + 3y^2 . (x+1)
= ( 3x^3y^2 + 3y^2 ) . ( x+1 )
= 3y^2 . ( x^3 + 1 ) . ( x+1 )
= 3y^2 . (x + 1) . (x2 - x + 1) . (x + 1)
= 3y^2 . (x + 1)^2 . (x2 - x + 1)
xin hay nhất ạ