Question

решите на множестве R уравнение 7-6x-9x²=8

Answer 1

$7 - 6x - 9 {x}^{2} = 8 \\ 7 - 6x - 9 {x}^{2} - 8 = 0 \\ - 1 - 6x + 9 {x}^{2} = 0 \\ 1 + 6x + 9 {x}^{2} = 0 \\ 9 {x }^{2} + 6x + 1 = 0 \\ (3x + 1) ^{2} = 0 \\ 3x + 1 = 0 \\ 3x = - 1 \\ x = - \frac{1}{3}$