(3х+1)(3х-1)-(х+2)(х-1)=8

Question

(3х+1)(3х-1)-(х+2)(х-1)=8

Answer 1

(3х+1)(3х-1)-(х+2)(х-1)=8

9x²-1-(x²-x+2x-2)=8

9x²-1-x²+x-2x+2-8=0

8x²-x-7=0

D=1+4*7*8=225

x=(1-15)/16=-14/16=-7/8

x=(1+15)/16=1

ответ: -7/8, 1