Question

Срочно дам много балов!

Answer 1

а)

$\frac{3b}{5b + 1} \\ 5b + 1 = 0 \\ 5b = - 1 \\ b = - 1 \div 5 \\ b = - 0.2 \\ b\neq - 0.2 \\ b \: \epsilon \: ( - \propto; \: - 0.2)U( - 0.2; \: + \propto)$

б)

$\frac{x + 2}{ {x}^{2} + 3x} \\ {x}^{2} + 3x = 0 \\x( x + 3) = 0 \\ x_{1} = 0\\ x_{2} = - 3 \\ x_{1}\neq0 \\ x_{2} \neq - 3 \\ x \: \epsilon \: ( - \propto; \: - 3)U( - 3; \: 0)U(0; \: + \propto)$

в)

$\frac{ - 5}{ {a}^{2} - 3 } \\ {a}^{2} - 3 = 0 \\ (a - \sqrt{3} )(a + \sqrt{3} ) = 0 \\a_{1} = \sqrt{3} \\ a_{2} = - \sqrt{3} \\ a _{1}\neq \sqrt{3} \\ a_{2} \neq - \sqrt{3} \\ a \: \epsilon \: ( - \propto; \: - \sqrt{3} )U( - \sqrt{3} ; \: \sqrt{3} )U( \sqrt{3} ; \: + \propto)$

г)

$\frac{4}{ {x}^{2} - 7x + 12 } \\ {x}^{2} - 7x + 12 = 0 \\ \\ po \: \: \: teoreme \: \: \: vieta \\ {x}^{2} + bx + c = 0\\ x_{1} + x_{2} = - b\\ x_{1} x_{2} = c \\ \\ x_{1} + x_{2} =7 \\ x_{1} x_{2} =12 \\ x_{1} = 3 \\ x_{2} = 4 \\ x_{1}\neq3 \\ x_{2}\neq4 \\ x \: \epsilon \: ( - \propto; \: 3)U(3; \: 4)U(4; \: + \propto)$