Câu `1:`
`a) (2x+3)^2 = (2x)^2 + 2 . 2x . 3 + 3^2 = 4x^2 + 12x + 9`
`b) (x/2 - 4)^2 = (x/2)^2 - 2 . x/2 .4 + 4^2 = (x^2)/4 - 4x + 16`
`c) (3x+2).(3x-2) = (3x)^2 - 2^2 = 9x^2 - 4`
`d) (3-x^2)^2 = 3^2 - 2 . 3 . x^2 + (x^2)^2 = 9 - 6x^2 + x^4`
Câu `2:`
`a) (3x+1)^2 = (3x)^2 + 2 . 3x . 1 + 1^2 = 9x^2 + 6x + 1`
`b) (x-3/4)^2 = x^2 - 2 . x . 3/4 + (3/4)^2 = x^2 - 3/2x + 9/16`
`c) (x-4).(x+4) = x^2 - 4^2 = x^2 -16`
`d) (x^2 - 2)^2 = (x^2)^2 - 2 . x^2 . 2 + 2^2 = x^4 - 4x^2 + 4`
Câu `3:`
`a) (2x+y)^2 = (2x)^2 + 2 . 2x . y + y^2 = 4x^2 + 4xy + y^2`
`b) (x-y/2)^2 = x^2 - 2 . y/2 . x + (y/2)^2 = x^2 - xy + (y^2)/4`
