24.Calculaţi:
a) (1-x)(1+x)(1+x²);
c) (a-√2)(a + √2)(a² + 2)(a* + 4);
b) (y-2)(y + 2)(y² + 4);
d) (16x^4+ 1)(4x² + 1)(2x + 1)(2x − 1).