6) (b^-4)^-1 × b^-4/(b^3)^-3 × b^8 = (b-4)^-1 × b^-4/ b^-9 × b^8 = (b-4)^-1 × b^-4/b^-1 = (b-4)^-1/b^3 = 1/b^3 × (b-4) = 1/b^4 - 4b^3
7) 0,7
8) 17
9) а) 1/4х^2 = 3х
х^2 = 12х
х^2 - 12х = 0
х(х-12) = 0
х=0
х-12=0
х1=0
х2=12
б) 7х^2 - 4х - 3= 0
7х^2 + 3х-7х-3 = 0
х(7х+3)-(7х+3)=0
(7х+3)(х-1)=0
7х+3=0
х-1=0
х1=-3/7
х2=1
