Решить неравенство

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Решить неравенство \frac{1-3^{ x^{2} +2x-3}}{x^{2} +2x-3} \leq 0


Алгебра (57 баллов) | 12 просмотров
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Правильный ответ
\frac{1-3^{x^2+2x-3}}{x^2+2x-3} \leq 0
let's t=x^2+2x-3

\frac{1-3^t}{t} \leq 0;

We have three possible cases:

first:

\left \{ {{\frac{1-3^t}{t} \leq 0|*t} \atop {t\ \textgreater \ 0}} \right. ; 
 \left \{ {{1-3^t \leq 0} \atop {t\ \textgreater \ 0}} \right. ; 
 \left \{ {{-3^t \leq -1} \atop {t\ \textgreater \ 0}} \right. ; 
 \left \{ {{3^t \geq 1} \atop {t\ \textgreater \ 0}} \right. ; 
 \left \{ {{3^t \geq 3^0} \atop {t\ \textgreater \ 0}} \right. ; 
 \left \{ {{t \geq 0} \atop {t\ \textgreater \ 0}} \right. ; 
t\ \textgreater \ 0

t=x^2+2x-3\ \textgreater \ 0

x^2+3x-x-3\ \textgreater \ 0

x(x+3)-(x+3)\ \textgreater \ 0

(x-1)(x+3)\ \textgreater \ 0

[x-(1)]*[x-(-3)]\ \textgreater \ 0

x\in (-\infty;-3)\cup(1;+\infty)

second:

\left \{ {{\frac{1-3^t}{t} \leq 0|*t} \atop {t\ \textless \ 0}} \right. ;
 \left \{ {{1-3^t \geq 0} \atop {t\ \textless \ 0}} \right. ;
 \left \{ {{-3^t \geq -1} \atop {t\ \textless \ 0}} \right. ;
 \left \{ {{3^t \leq 1} \atop {t\ \textless \ 0}} \right. ;
 \left \{ {{3^t \leq 3^0} \atop {t\ \textless \ 0}} \right. ;
 \left \{ {{t \leq 0} \atop {t\ \textless \ 0}} \right. ;
t\ \textless \ 0

t=x^2+2x-3 \ \textless \ 0

[x-(1)]*[x-(-3)]\ \textless \ 0

x\in (-3;1)

third:

\left \{ {{ \frac{1-3^t}{t} \leq 0} \atop {t=0}} \right. ;
 \left \{ {{ \frac{1-3^0}{0} \leq 0} \atop {t=0}} \right. ;
 \left \{ {{ \frac{0}{0} \leq 0} \atop {t=0}} \right.

The system of inequalities behind have not sense due to its first inequality.
----------------------------------
So, we have: t\in (-\infty;0)\cup(0;+\infty)

and x^2+2x-3 \neq 0;

(x-1)(x+3) \neq 0

x\in (-\infty;-3)\cup(-3;1)\cup(1;+\infty)

Answer: (-\infty;-3)\cup(-3;1)\cup(1;+\infty)
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Решение смотри на фото.


image
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