a) `(2x - 3)(x^3 - x^2 + 2)`
`= 2x^4 - 2x^3 + 4x - 3x^3 + 3x^2 - 6`
`= 2x^4 - 5x^3 + 3x^2 + 4x - 6`
b) `(2+1)(2^2 + 1)(2^4 + 1)...(2^256 + 1)`
`= (2^2 - 1)(2^2 + 1)(2^4 + 1)...(2^256 + 1)`
`= (2^4 - 1)(2^4 + 1)...(2^256 + 1)`
`= (2^256 - 1)(2^256 + 1)`
`= 2^512 - 1`