145.2
A = log(2-x) 27 - log(x-2)^4 9 = 0,625
2-x >0 ; 2-x ≠1 ⇒ x<2 ; x≠1 <br> log(x-2)^4 9 = log(2-x)^4 9 = [log(2-x) 9] /[log(2-x) (2-x)^4] =
= [log(2-x) 9] /4
⇒ 4·[log(2-x) 3³] - log(2-x) 3² = 2,5
log(2-x) 3^12 - log(2-x) 3² = 2,5
log(2-x) (3^12 /3²) = log(2-x) 3^10 = 10·log(2-x) 3 = 2,5
log(2-x) 3 = 0,25
4·log(2-x) 3 = 1
log((2-x) 3^4 = 1
2-x = 3^4 = 81
x = -79
147.2
B=[log(2) x]^4 + 3[log(2) x]² -4 = 0
x>0 ; обозначим [log(2) x]² =y ⇒
y² +3y -4 =0
(y-1)·(y+4)=0 ⇒
y1= 1 ⇔ [log(2) x]² = 1 ⇒ log(2) x = +/-1 ⇒
log(2) x1 = 1 ⇔ x1 = 2
log(2) x2 = -1 ⇔ x2 = 1/2
y2 = -4 не уд., т.к [log(2) x]² >0
Ответ: 2 ; 0,5