100 . решите уравнение 12х^2-5х+(1+3х)(1-3х)-3(х-2)(х+3)-6=21

(12-х)-(3х+4)=-х-1

12-x-3x-4=-x-1

8+1=-x+x+3x

9=3x

x=3

12x² - 5x + ( 1 + 3x)(1 - 3x) - 3( x - 2)(x + 3) - 6 = 21
12x² - 5x + 1 -9x² - 3( x² + x -6) - 6 = 21
3x² - 5x + 1 - 3x² - 3x + 18 - 6 = 21
- 8x = 21 - 13
- 8x = 8
8x = - 8
x = - 1