Question

Решите уравнение:(7х+1)(х-3) +20(х-1)(х+1)=3(3х-2)²+13​

Answer 1

Ответ:

${7x}^{2} - 21x + x - 3 + 20x ^{2} - 20 = 3(9x ^{2} - 12x + 4) + 13 \\ 27 x^{2} - 20x - 23 = 27x ^{2} - 36x + 12 + 13 \\ 27 {x}^{2} - 20x - 27 {x}^{2} + 36x = 12 + 13 + 23 \\ 16x = 48 \\ x = 3$

Answer 2

$(7x + 1)(x - 3) + 20(x - 1)(x + 1) = 3 {(3x - 2)}^{2} + 13 \\ {7x}^{2} - 21x + x - 3 + 20( {x}^{2} - 1) = 3( {9x}^{2} - 12x + 4) + 13 \\ {7x}^{2} - 21x + x - 3 + {20x}^{2} - 20 = {27x}^{2} - 36x + 12 + 13 \\ {27x}^{2} - 20x - 23 = {27x}^{2} - 36x + 25 \\ - 20x - 23 = - 36x + 25 \\ - 20x + 36x = 25 + 23 \\ 16x = 48 \\ x = 3$