Log2 (7-x)=5 ОДЗ: 7-x>0 x<7
log2 (7-x)=5log2 2
log2 (7-x)=log2 32
7-x=32
x=7-32
x=-25
1)
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1 решение
2)
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3)
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бесконечное множество решений
1) t =((3- 2x)/(5x+1))² ;
t = 82/9 - 1/t ;
t +1/t = 82/9 ; **** [ t² - 82/9t +1 =0] ***
t +1/t =9 +1/9 ;
[ t =9 ; t =1/9.
a) ((3- 2x)/(5x+1))² =9 .
[(3- 2x)/(5x+1) = - 3 ;(3- 2x)/(5x+1) = 3 . [ x = -6/13 ;x =0.
b) ((3- 2x)/(5x+1))² =1/9.
[(3- 2x)/(5x+1) = -1/ 3 ;(3- 2x)/(5x+1) = 1/3. [ x = 10 ; x =8/11.
ответ : - 6/13 ;0 ; 8/11 ;10.
2) (x/(x-1))² + (x/(x +1))² =45/16;
(x/(x -1) + x/(x+1))² - 2*x/(x-1)*x/(x+1) =45/16 ;
(2x²/(x² -1))² -2x²/(x² -1) =45/16 ;
t =2x²/(x² -1);
t² - t -45/16 =0;
t₁ = -5/4 ;
t₂ = 9/4 .
a) 2x²/(x² -1) = -5/4 не имеет решения ю
b) 2x²/(x² -1) = 9/4 ⇒ x ₁= - 3 ; x₂ =3;
ответ : - 3 ;3 .
------------------------------- или ---------------------------
(1+1/(x-1))² + (1 - 1/(x+1))² =45/16 ;
. . .
1
а) 72
б)729
в)9
г)1
д)44
3.
а)256а¹⁶b¹²/81
б)