7^(x - 5) > 3^(x² + x - 30)
--------------------
разложим x² + x - 30 = (x + 6)(x - 5)
D=1 + 120 = 121 = 11²
x₁₂ = (-1 +- 11)/2 = -6 и 5
-----------
7^(x - 5) > 3^(x + 6)(x - 5)
прологарифмируем по основанию допустим 7
log(7) 7^(x - 5) > log(7) 3^(x + 6)(x - 5)
(x - 5) - (x + 6)(x - 5) log(7) 3 > 0
(x - 5) (xlog(7) 3 + 6log(7) 3 - 1) > 0
корни 5 и (1 - 6log(7) 3)/log(7) 3 < 0
(1 - 6log(7) 3)/log(7) 3 < x < 5
Copyright © 2024 SCHOLAR.TIPS - All rights reserved.
Answers & Comments
Verified answer
7^(x - 5) > 3^(x² + x - 30)
--------------------
разложим x² + x - 30 = (x + 6)(x - 5)
D=1 + 120 = 121 = 11²
x₁₂ = (-1 +- 11)/2 = -6 и 5
-----------
7^(x - 5) > 3^(x + 6)(x - 5)
прологарифмируем по основанию допустим 7
log(7) 7^(x - 5) > log(7) 3^(x + 6)(x - 5)
(x - 5) - (x + 6)(x - 5) log(7) 3 > 0
(x - 5) (xlog(7) 3 + 6log(7) 3 - 1) > 0
корни 5 и (1 - 6log(7) 3)/log(7) 3 < 0
(1 - 6log(7) 3)/log(7) 3 < x < 5
(1 - 6log(7) 3)/log(7) 3 < x < 5
(1 - 6log(7) 3)/log(7) 3 эта фигня равна примерно -4.4
5 не входит