5^(1/x)*2^x>10 (неравенство) Учитель очень удивится увидев твоё верное решение 😼 Укажите решение неравенства: 5^(1/x)*2^x>10 (множество решений неравенства)
Решение
Подробное решение
Дано неравенство:2 x 5 1 x > 10 2^{x} 5^{\frac{1}{x}} > 10 2 x 5 x 1 > 10 Чтобы решить это нер-во - надо сначала решить соотвествующее ур-ние:2 x 5 1 x = 10 2^{x} 5^{\frac{1}{x}} = 10 2 x 5 x 1 = 10 Решаем:x 1 = 1 2 log ( 2 ) ( − − log ( 5 log ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) x_{1} = \frac{1}{2 \log{\left (2 \right )}} \left(- \sqrt{- \log{\left (5^{\log{\left (16 \right )}} \right )} + \log^{2}{\left (10 \right )}} + \log{\left (10 \right )}\right) x 1 = 2 log ( 2 ) 1 ( − − log ( 5 l o g ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) x 2 = 1 2 log ( 2 ) ( − log ( 5 log ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) x_{2} = \frac{1}{2 \log{\left (2 \right )}} \left(\sqrt{- \log{\left (5^{\log{\left (16 \right )}} \right )} + \log^{2}{\left (10 \right )}} + \log{\left (10 \right )}\right) x 2 = 2 log ( 2 ) 1 ( − log ( 5 l o g ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) x 1 = 1 2 log ( 2 ) ( − − log ( 5 log ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) x_{1} = \frac{1}{2 \log{\left (2 \right )}} \left(- \sqrt{- \log{\left (5^{\log{\left (16 \right )}} \right )} + \log^{2}{\left (10 \right )}} + \log{\left (10 \right )}\right) x 1 = 2 log ( 2 ) 1 ( − − log ( 5 l o g ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) x 2 = 1 2 log ( 2 ) ( − log ( 5 log ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) x_{2} = \frac{1}{2 \log{\left (2 \right )}} \left(\sqrt{- \log{\left (5^{\log{\left (16 \right )}} \right )} + \log^{2}{\left (10 \right )}} + \log{\left (10 \right )}\right) x 2 = 2 log ( 2 ) 1 ( − log ( 5 l o g ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) Данные корниx 1 = 1 2 log ( 2 ) ( − − log ( 5 log ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) x_{1} = \frac{1}{2 \log{\left (2 \right )}} \left(- \sqrt{- \log{\left (5^{\log{\left (16 \right )}} \right )} + \log^{2}{\left (10 \right )}} + \log{\left (10 \right )}\right) x 1 = 2 log ( 2 ) 1 ( − − log ( 5 l o g ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) x 2 = 1 2 log ( 2 ) ( − log ( 5 log ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) x_{2} = \frac{1}{2 \log{\left (2 \right )}} \left(\sqrt{- \log{\left (5^{\log{\left (16 \right )}} \right )} + \log^{2}{\left (10 \right )}} + \log{\left (10 \right )}\right) x 2 = 2 log ( 2 ) 1 ( − log ( 5 l o g ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) являются точками смены знака неравенства в решениях. Сначала определимся со знаком до крайней левой точки:x 0 < x 1 x_{0} < x_{1} x 0 < x 1 Возьмём например точкуx 0 = x 1 − 1 10 x_{0} = x_{1} - \frac{1}{10} x 0 = x 1 − 10 1 = __________________________
/ 2 / log(16)\
- \/ log (10) - log\5 / + log(10) 1
----------------------------------------- - --
1 10
2*log (2) =− 1 10 + 1 2 log ( 2 ) ( − − log ( 5 log ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) - \frac{1}{10} + \frac{1}{2 \log{\left (2 \right )}} \left(- \sqrt{- \log{\left (5^{\log{\left (16 \right )}} \right )} + \log^{2}{\left (10 \right )}} + \log{\left (10 \right )}\right) − 10 1 + 2 log ( 2 ) 1 ( − − log ( 5 l o g ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) подставляем в выражение2 x 5 1 x > 10 2^{x} 5^{\frac{1}{x}} > 10 2 x 5 x 1 > 10 1
----------------------------------------------
__________________________ __________________________
/ 2 / log(16)\ / 2 / log(16)\
- \/ log (10) - log\5 / + log(10) 1 - \/ log (10) - log\5 / + log(10) 1
----------------------------------------- - -- ----------------------------------------- - --
1 10 1 10
2*log (2) 2*log (2)
5 *2 > 10 1
------------------------------------------------
__________________________ __________________________
/ 2 / log(16)\ / 2 / log(16)\
1 - \/ log (10) - log\5 / + log(10) 1 - \/ log (10) - log\5 / + log(10) > 10
- -- + ----------------------------------------- - -- + -----------------------------------------
10 2*log(2) 10 2*log(2)
2 *5
значит одно из решений нашего неравенства будет при:x < 1 2 log ( 2 ) ( − − log ( 5 log ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) x < \frac{1}{2 \log{\left (2 \right )}} \left(- \sqrt{- \log{\left (5^{\log{\left (16 \right )}} \right )} + \log^{2}{\left (10 \right )}} + \log{\left (10 \right )}\right) x < 2 log ( 2 ) 1 ( − − log ( 5 l o g ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) _____ _____
\ /
-------ο-------ο-------
x1 x2 Другие решения неравенства будем получать переходом на следующий полюс и т.д. Ответ:x < 1 2 log ( 2 ) ( − − log ( 5 log ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) x < \frac{1}{2 \log{\left (2 \right )}} \left(- \sqrt{- \log{\left (5^{\log{\left (16 \right )}} \right )} + \log^{2}{\left (10 \right )}} + \log{\left (10 \right )}\right) x < 2 log ( 2 ) 1 ( − − log ( 5 l o g ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) x > 1 2 log ( 2 ) ( − log ( 5 log ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) x > \frac{1}{2 \log{\left (2 \right )}} \left(\sqrt{- \log{\left (5^{\log{\left (16 \right )}} \right )} + \log^{2}{\left (10 \right )}} + \log{\left (10 \right )}\right) x > 2 log ( 2 ) 1 ( − log ( 5 l o g ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) )
Решение неравенства на графике
-22.5 -20.0 -17.5 -15.0 -12.5 -10.0 -7.5 -5.0 -2.5 0.0 2.5 5.0 0 3e264
/ / __________________________ \ / __________________________ \\
| | / 2 / log(16)\ | | / 2 / log(16)\ ||
| | - \/ log (10) - log\5 / + log(10)| | \/ log (10) - log\5 / + log(10) ||
Or|And|0 < x, x < -----------------------------------------|, And|x < oo, --------------------------------------- < x||
\ \ 2*log(2) / \ 2*log(2) // ( 0 < x ∧ x < 1 2 log ( 2 ) ( − − log ( 5 log ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) ) ∨ ( x < ∞ ∧ 1 2 log ( 2 ) ( − log ( 5 log ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) < x ) \left(0 < x \wedge x < \frac{1}{2 \log{\left (2 \right )}} \left(- \sqrt{- \log{\left (5^{\log{\left (16 \right )}} \right )} + \log^{2}{\left (10 \right )}} + \log{\left (10 \right )}\right)\right) \vee \left(x < \infty \wedge \frac{1}{2 \log{\left (2 \right )}} \left(\sqrt{- \log{\left (5^{\log{\left (16 \right )}} \right )} + \log^{2}{\left (10 \right )}} + \log{\left (10 \right )}\right) < x\right) ( 0 < x ∧ x < 2 log ( 2 ) 1 ( − − log ( 5 l o g ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) ) ∨ ( x < ∞ ∧ 2 log ( 2 ) 1 ( − log ( 5 l o g ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) < x ) __________________________ __________________________
/ 2 / log(16)\ / 2 / log(16)\
- \/ log (10) - log\5 / + log(10) \/ log (10) - log\5 / + log(10)
(0, -----------------------------------------) U (---------------------------------------, oo)
2*log(2) 2*log(2) x ∈ ( 0 , 1 2 log ( 2 ) ( − − log ( 5 log ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) ) ∪ ( 1 2 log ( 2 ) ( − log ( 5 log ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) , ∞ ) x \in \left(0, \frac{1}{2 \log{\left (2 \right )}} \left(- \sqrt{- \log{\left (5^{\log{\left (16 \right )}} \right )} + \log^{2}{\left (10 \right )}} + \log{\left (10 \right )}\right)\right) \cup \left(\frac{1}{2 \log{\left (2 \right )}} \left(\sqrt{- \log{\left (5^{\log{\left (16 \right )}} \right )} + \log^{2}{\left (10 \right )}} + \log{\left (10 \right )}\right), \infty\right) x ∈ ( 0 , 2 log ( 2 ) 1 ( − − log ( 5 l o g ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) ) ∪ ( 2 log ( 2 ) 1 ( − log ( 5 l o g ( 16 ) ) + log 2 ( 10 ) + log ( 10 ) ) , ∞ )