`a) 6x^2 - 4x^2(x^2 - 3x - 2)`
` = 6x^2 - (4x^4 - 12x^3 - 8x^2)`
` = 6x^2 - 4x^4 + 12x^3 + 8x^2`
` = 14x^2 - 4x^4 + 12x^3`
`b) (3x-2)^2 - 2(x-1)^2`
` = 9x^2 - 12x + 4 - 2(x^2 - 2x + 1)`
` = 9x^2 - 12x + 4 - 2x^2 + 4x -2`
` = 7x^2 - 8x + 2`
`c) ( 2x^4 + 5x + x^3 - 2 - 2 - 3x^2 ) : ( x^2 + 1 - x )`