Question

ПОМОГИТЕ ПОЖАЛУЙСТА!!​

Answer 1

Объяснение:

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Answer 2

Ответ:

$\left\{\begin{array}{l}x_3+x_4=19\\x_2\cdot x_5=70\end{array}\right\ \ \left\{\begin{array}{l}(x_1+2d+(x_1+3d)=19\\(x_1+d)\cdot (x_1+4d)=70\end{array}\right\ \ \left\{\begin{array}{l}2x_1+5d=19\\x_1^2+5dx_1+4d^2=70\end{array}\right$

$\left\{\begin{array}{l}x_1=9,5-2,5d\\(9,5-2,5d)^2+5d(9,5-2,5d)+4d^2=70\end{array}\right\ \ \left\{\begin{array}{l}x_1=9,5-2,5d\\2,25d^2=20,25\end{array}\right$

$\left\{\begin{array}{l}x_1=9,5-2,5d\\d\, ^2=9\end{array}\right\ \ \left\{\begin{array}{l}x_1^{(1)}=17\ \ ili\ \ \ x_1^{(2)}=2\\d_1=-3\ \ ili\ \ d_2=3\end{array}\right\\\\\\\{x_{n}\}\ -\ vozrastaet\ \ \ \Rightarrow \ \ \ x_1<x_2<\, ...\, <x_7<\, ...\ \ \Rightarrow \ \ d=3\ ,\ x_1=2\\\\x_7=x_1+6d=2+6\cdot 3=20\ \ ,\ \ \ \boxed{\ x_7=20\ }$