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`a,`
`(3x-2y)^2`
`= (3x)^2 - 2 . 3x . 2y + (2y)^2`
`= 9x^2 - 12xy + 4y^2`
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`b,`
`(2x-1/2)^3`
`= (2x)^3 - 3. (2x)^2 . 1/2 + 3 . 2x . (1/2)^2 - (1/2)^3`
`= 8x^3 - 3 . 4x^2 . 1/2 + 3 . 2x . 1/4 - 1/8`
`= 8x^3 - 6x^2 + 3/2 x - 1/8`
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`c,`
`(x+3)(x^2 - 3x + 9)`
`= (x+3)(x^2 - 3 x +3^2)`
`= x^3 +3^3`
`=x^3 + 27`