\[\boxed{\mathbf{2}\mathbf{.}}\]
\[\textbf{а)}\ y = x + 1;\ \ x = y - 1\]
\[\textbf{б)}\ y = 2x;\ \ x = \frac{1}{2}y\]
\[\textbf{в)}\ y = x^{2};\ \ \lbrack 0; + \infty);\]
\[x = \sqrt{y};\ \ \lbrack 0; + \infty);\]
\[\textbf{г)}\ y = x^{2};\ \ ( - \infty;0\rbrack;\]
\[x = - \sqrt{y};\ \ \lbrack 0; + \infty);\]
\[\textbf{д)}\ y = x^{3};\ \ \ x = \sqrt[3]{y}\]
\[\textbf{е)}\ y = 2^{x};\ \ \]
\[x = \log_{2}y;\ \ (0; + \infty);\]