\[\boxed{\mathbf{582}.}\]
\[1)\ y = \sqrt{x^{2} - 3x + 2}\]
\[x^{2} - 3x + 2 \geq 0\]
\[D = 9 - 8 = 1\]
\[x_{1} = \frac{3 + 1}{2} = 2;\ \ \]
\[x_{2} = \frac{3 - 1}{2} = 1.\]
\[(x - 1)(x - 2) \geq 0\]
\[x \leq 1;\ \ \ x \geq 2.\]
\[2)\ y = \sqrt{x^{2} + 5x - 6}\]
\[x^{2} + 5x - 6 \geq 0\]
\[x_{1} + x_{2} = - 5;\ \ x_{1} \cdot x_{2} = - 6\]
\[x_{1} = - 6;\ \ \ x_{2} = 1.\]
\[(x + 6)(x - 1) \geq 0\]
\[x \leq - 6;\ \ x \geq 1.\]
\[3)\ y = \frac{1}{x^{2} + 7x - 8}\]
\[x^{2} + 7x - 8 \neq 0\]
\[x_{1} + x_{2} = - 7;\ \ x_{1} \cdot x_{2} = - 8\]
\[x_{1} \neq - 8;\ \ \ x_{2} \neq 1.\]
\[4)\ y = \frac{2}{2x^{2} + 7x - 4}\]
\[2x^{2} + 7x - 4 \neq 0\]
\[D = 49 + 32 = 81\]
\[x_{1} \neq \frac{1}{2};\ \ \ x_{2} \neq - 4.\]