Question

5. Розв’яжіть рівняння: (2x - 3)(2x + 3) - (x - 2)(x + 1) = 7
помогите пж!!​

Answer 1

$(2x -3 )(2x + 3) - (x - 2)(x + 1) = 7 \\ (2x) {}^{2} - 3 {}^{2} - ( {x}^{2} + x - 2x - 2) - 7 = 0 \\ 4 {x}^{2} - 9 - {x}^{2} + x + 2 - 7 = 0 \\ 3 {x}^{2} + x - 14 = 0 \\ a = 3\\ b = 1\\ c = - 14 \\ D = {b}^{2} - 4ac = 1 { }^{2} - 4 \times 3 \times ( - 14) = \\ = 1 + 168 = 169 \\ x_{1} = \frac{ - 1 + 13}{2 \times 3} = \frac{12}{6} = 2\\ x_{2} = \frac{ - 1 - 13}{2 \times 3} = - \frac{14}{6} = - \frac{7}{3} = - 2 \frac{1}{3}$