1) log12 (x^2-8x+16) = 0

2) log1/2 (x^2+3x-1) = - 2

1) log12 (x²-8x+16) = 0

log12 (x²-8x+16) = log12 (1)

x²-8x+16=1

x²-8x+15=0

по теореме Виетта

x1+x2=8

x1*x2=15

x1=3

x2=5

ответ: 3; 5

2) log1/2 (x²+3x-1) = - 2

loa1/2 (x²+3x-1) = log1/2 (4)

x²+3x-1=4

x²+3x-5=0

D=b²-4ac=3²-4*1 * (-5) = 9+20=29

x1 = (-b+√D) / 2a = (-3+√29) / 2

x2 = (-b-√D) / 2a = (-3-√29) / 2<0

ответ: (-3+√29) / 2