Nhờ các cao nhân giúp tui chớ tui quên r

`(x+3y)^2`

`= x^2 + 2x . 3y + (3y)^2`

`= x^2 + 6xy + 9y^2`

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`(2xy + 1)^2`

`= (2xy)^2 + 2 . 2xy . 1 + 1^2`

`= 4x^2y^2 + 4xy + 1`

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`(2xy + 2)^2`

`= (2xy)^2 + 2 . 2xy . 2 + 2^2`

`= 4x^2y^2 + 8xy + 4`

``

`(2xy + 3)^2`

`= (2xy)^2 + 2 . 2xy . 3 + 3^2`

`= 4x^2y^2 + 12xy + 9`

``

`(4 + 2b)^2`

`= 4^2 + 2 . 4 . 2b + (2b)^2`

`= 16 + 16b + 4b^2`

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`(a + 3b)^2`

`= a^2 + 2 . a . 3b + (3b)^2`

`= a^2 + 6ab + 9b^2`

``

`(m + 2n)^2`

`= m^2 + 2m . 2n + (2n)^2`

`= m^2 + 4mn + 4n^2`

`@ HĐT: (a+b)^2 = a^2 + 2ab + b^2`