5. 9^(x² -3x) =81^(-5/8) ; 9^(x² -3x) =9^(-5/4) ;x² -3x = - 5/4 ;4x² - 12x +5 = 0 ;x₁ =(6 -√(6² - 4*5))/4 = 1/2;x₂ =(6+√(6² - 4*5))/4 = 5/2 .min(x) =1/2.------- 6. (1/3)^(x²-9x+10) = 1/9 ;(1/3)^(x²-9x+10) = (1/3)² ;x²-9x+10 =2 ;x²-9x+8 =0 ; * * * D =9² - 4*8 =81 -32 = 49 =7² >0 * * *(x₁ +x₂)/2=9/2 =4,5 (по теореме Виета);* * * * * * *
x₁ = 1 ; x₂ = 8. ⇒(x₁ +x₂)/2=(1+8)/2 =4.5.-------7. (0,2)^(x) *(0,2)³ =(0,2)^(2x) / (0,2)⁵ ;(0,2)^(x+3)=(0,2)^(2x-5) ;x+3 = 2x-5 ;x =8.-------8. f(x)= 2,75^(8x+2) ≤ 16/121 ; f(x)= 2,75^(8x+2) ≥ 16/121 ⇒f(x)= 2,75^(8x+2) = 16/121 . (11/4) ^(8x+2) = 16/121 ;(11/4) ^(8x+2) =(11/4) ^(-2) ;8x+2 = -2 ;8x = - 4 ; x = -1/2 .* * * * * * * УДАЧИ !!!