Question

решыть уровнение    (3х+1)(3х-1)-(х+2)(х-1)=8

Answer 1

(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