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Laster_Alex

Z8

Sep 17th, 2023
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  1. 1)
  2. По УРК5 $$\sqrt{x+7}\ge 0.5(x-1)⟺\left[\begin{array}{l}\left\{\begin{array}{l}0.5(x-1)<0\\ x+7\ge 0\end{array}\right.\\ \left\{\begin{array}{l}0.5(x-1)\ge 0\\ x+7\ge 0.25({x}^{2}-2x+1)\end{array}\right.\end{array}\right.⟺\left[\begin{array}{l}\left\{\begin{array}{l}x<1\\ x\ge -7\end{array}\right.\\ \left\{\begin{array}{l}x\ge 1\\ 4x+28\ge {x}^{2}-2x+1\end{array}\right.\end{array}\right.⟺\left[\begin{array}{l}x\in \left[-7;1\right)\\ \left\{\begin{array}{l}x\ge 1\\ {x}^{2}-6x-27\le 0\end{array}\right.\end{array}\right.$$
  3.  
  4. 2)
  5. Решим квадратное уравнение:
  6. $$x=3\pm \sqrt{9+27}=3\pm 6=-3;9$$
  7. Т.к. старший коэфф. >0, $$x\in \left[-3;9\right]$$
  8.  
  9. 3)
  10. Выходит:
  11. $$\left[\begin{array}{l}x\in \left[-7;1\right)\\ \left\{\begin{array}{l}x\ge 1\\ x\in \left[-3;9\right]\end{array}\right.\end{array}\right.\Rightarrow x\in \left[-7;9\right]$$
  12. Длина данного промежутка 16
  13.  
  14.  
  15. Ответ:
  16. 16
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