Question

решите уравнение: (3х+1)(3х-1)-(х+2)(х-2)=8

Answer 1

(3х+1)(3х-1)-(х+2)(х-2)=8

9x²-1-(x²-4)=8

9x²-1-x²+4=8

8x²=5

x²=5/8

x=±√5/√8

ответ: ±√5/√8

Answer 2

т.к(a-b)(a+b)=a^2-b^2,
то (3х-1)(3х+1)=9х^2-1
а (х-2)(х+2)=х^2-4
и (3х+1)(3х-1)-(х+2)(х-2)=
(9х^2-1)-(х^2-4)=
9х^2-1-х^2+4=
8х^2+3=8
8х^2=5
х^2=5/8=10/16
х1=(√10)/4
х2=-(√10)/4