`a)`
`4x^2 (2x^3 - x+ 3)`
` = 8x^5 - 4x^3 + 12x^2`
``
`b)`
`(2x-3)(4x^2 - 6x + 9) - 8(x^3 + 3)`
` = 8x^3 - 12x^2 + 18x - 12x^2 + 18x - 27 - 8x^3 - 24`
` = (8x^3 - 8x^3) + (-12x^2 - 12x^2) + (18x + 18x) - (27 + 24)`
` = -24x^2 + 36x - 51`
``
`c)`
`(x-2)^2 - 2(x+2)(x-1) + (x+1)`
`(x^2 - 2 . x . 2 + 2^2) - (2x + 4)(x-1) + (x+1)`
`= (x^2 - 4x + 4) - (2x^2 - 2x + 4x - 4) + (x+1)`
` = x^2 - 4x + 4 - 2x^2 + 2x - 4x + 4 + x + 1`
`= (x^2 - 2x^2) +(-4x - 4x + 2x +x) + (4 + 4+1)`
` = -x^2 - 5x + 9`
