`a, 2x ( 3x^2 - 4x + 2 )`
`= ( 2x . 3x^2 ) + [ 2x . ( -4x ) ] + ( 2x . 2 )`
`= 6x^3 - 8x^2 + 4x`
`b, 2x ( 3x + 5 ) - 3 ( 2x^2 - x + 2 )`
`= ( 2x . 3x ) + ( 2x . 5 ) + ( - 3 . 2x^2 ) + [ ( -3 ) . ( -x ) ] + ( - 3 . 2 )`
`= 6x^2 + 10x - 6x^2 + 3x - 6`
`= ( 6x^2 - 6x^2 ) + ( 10x + 3x ) - 6`
`= 13x - 6`
`c, ( 2x + 1 ) ( 3x^2 - x + 2 )`
`= ( 2x . 3x^2 ) + [ 2x . ( - x ) ] + ( 2x . 2 ) + ( 1 . 3x^2 ) + [ 1 . ( - x ) ] + ( 1 . 2 )`
`= 6x^3 - 2x^2 + 4x + 3x^2 - x + 2`
`= 6x^3 + ( - 2x^2 + 3x^2 ) + ( 4x - x ) + 2`
`= 6x^3 + x^2 + 3x + 2`