Đề bài yêu cầu gì thế em?
`x^2 +4xy+ 4y^2 -9`
`= (x^2 + 2x.2y + 4y^2) -9`
`= (x+2y)^2 - 3^2`
`= (x+2y -3)(x+2y +3)`
x2 + 4xy + 4y2 - 9
= (x2 + 4xy + 4y2)-32
= (x+2y)2 - 32
= (x+2y-3).(x+2y+3)
x2+4xy+4y2−9x2+4xy+4y2-9
=(x2+2x.2y+4y2)−9=(x2+2x.2y+4y2)-9
=(x+2y)2−32=(x+2y)2-32
=(x+2y −3)(x+2y+3)