Question

Решить уравнение: (1+3х)(9х²-3х+1)-3(3х+2)(3х-2)=13

Answer 1

$9x {}^{2} - 3x + 1 + 27x {}^{3 } - 9x {}^{2} + 3x - 3(9x {}^{2} - 4) = 13 \\ 1 + 27x {}^{3} - 27x {}^{2} + 12 = 13 \\ 13 + 27x {}^{3} - 27x {}^{2} = 13 \\ 27x {}^{3} - 27x {}^{2} = 0 \\ 27x {}^{2} (x - 1) = 0 \\ x {}^{2} (x - 1) = 0 \\ x {}^{2} = 0 \\ x - 1 = 0 \\ x = 0 \\ x = 1$