решыть уровнение (3х+1)(3х-1)-(х+2)(х-1)=8
(3х+1)(3х-1)-(х+2)(х-1)=8
9x²-3x+3x-1-(x²-x+2x-2)=8
9x²-3x+3x-1-x²+x-2x+2=8
8x²-x+1=8
8x²-x-7=0
x²-1/8x-7/8=0
x₁ x₂=1/16±√1/256+7/8
x₁=1/16+15/16=1
x₂=1/16-15/16=-7/8≈-0,875
9x^2-1-(x^2+2x-x-2)=8
9x^2-9-x^2-x+2=0
8x^2-x-7=0
D=1+4*7*8=1+224=225
x1=(1-15)/16=-14/16=-7/8
x2=(1+15)/16=16/16=1
Ответ: x1=-7/8; x2=1