Решите неравенства,пожалуйста. С 12-го задания.

Решите задачу:

$12.\\ (2 x -5)(x-3) \geq 0 \\ \left \{ {{2 x -5 \geq 0} \atop {x-3 \geq 0} \right. \\ \left \{ {{2x \geq5 } \atop {x \geq 3}} \right. \\ \left \{ {{x \geq \frac{5}{2} } \atop {x \geq 3}} \right. \\ \\ 13.\\ \frac{2x-7}{4-x} \geq 0 \\ \left \{ {{2x-7 \geq 0} \atop {4-x \neq 0}} \right \\ \left \{ {{2x \geq 7} \atop {-x \neq -4}} \right \\ \left \{ {{x \geq \frac{7}{2} } \atop {x \neq 4}} \right. \\$

$14. \\ \left \{ {{5x+13 \leq 0} \atop {x+5 \geq 1}} \right \\ \left \{ {{5x \leq -13} \atop {x \geq 1-5}} \\ \\ \left \{ {{x \leq - 2,6 } \atop {x \geq -4}} \right.$

$16. \\ \left \{ {{2x-3 \leq 5} \atop {7-3x \leq 1}} \right. \\ \left \{ {{2x \leq 5+3} \atop {-3x \leq 1-7}} \right. \\ \left \{ {{2x \leq 8} \atop {-3x \leq -6}} \right. \\ \left \{ {x \leq 4} \atop {x \geq 2}} \right. \\ \\$

$\\17. \\ \left \{ {{x^{2} \leq 4} \atop {x+3 \geq 0}} \right. \\ \left \{ {{ x^{2} \leq 4} \atop {x \geq -3}} \right. \\ \left \{ {{-2 \leq x \leq 2} \atop {x \geq -3}} \right. \\ \\$

$18. \\ x^{2} -4x+3 \geq 0 \\ x_{1} + x_{2}= \frac{-b}{a} \\ x_{1} * x_{2}= \frac{c}{a} \\ \\ x_{1} + x_{2}= 4 \\ x_{1} * x_{2}=3 \\ x_{1} \geq 3 \\ x_{2} \geq 1$