`a, 3(2^2 + 1)(2^4 + 1)(2^8 + 1)(2^16 + 1)`
`= 3 . 5 . 17 . 257 . 65537`
`= 4294967295`
`b, x(2x^2 - 3) - x^2(5x + 1) + x^2`
`= 2x^2 - 3x - 5x^3 - x^2 + x^2`
`= -5x^3 + 2x^2 - 3x`
`c, 3x(x - 2) - 5x(1 - x) - 8(x^2 - 3)`
`= 3x^2 - 6x - 5x + 5x^2 - 8x^2 + 24`
`= -11x + 24`