GreatFilter (х+6)(х²-8х+16)=9(4-х)
(х+6)(х-4)(x-4)-9(4-х)=0
(х+6)(х-4)(x-4)+9(x-4)=0
(x-4)((х+6)(х-4)+9)=0
(x-4)(x²+6x-4x-24+9)=0
(x-4)(x²+2x-15)=0

x-4=0
x²+2x-15=0

x=4
x²+2x-15=0

x²+2x-15=0
x₁+x₂= -2
xx₂= -15
x₁=-5
x₂=3

x₁=  -5
x₂=3
x₃=4