Fie [tex]A(x)=\left([tex]\begin{array}{cc}1-2 x & 2 x \\ x & 1+x\end{array}\right), x \in \mathbb{R}[/tex]. Arătați că:[/tex]

a) [tex]A(x) A(y)=A(1-(1-x)(1-y)), x, y \in \mathbb{R}[/tex];

b) [tex]A\left(x_{1}\right) A\left(x_{2}\right) \ldots A\left(x_{n}\right)=A\left(1-\left(1-x_{1}\right)\left(1-x_{2}\right) \ldots\left(1-x_{n}\right)\right), x_{k} \in \mathbb{R}, k=1, n, n \in \mathbb{N} *[/tex].