Помогите плиз (2x+1)(x+2)-(x-1)(3x+1)=0

Решите задачу:

$(2x+1)(x+2)-(x-1)(3x+1)=0 \\ 2 {x}^{2} + x + 4x + 2 - (3 {x}^{2} + x - 3x - 1) = 0 \\ 2 {x}^{2} + x + 4x + 2 - 3 {x}^{2} - x + 3x + 1) = 0 \\ - {x}^{2} + 7x + 3 = 0 \\ {x}^{2} - 7x - 3 = 0 \\ d = {b}^{2} - 4ac \\ d = 49 - 4 \times 1 \times ( - 3) = 49 + 12 = 61 \\ x_{1} = \frac{7 - \sqrt{61} }{2} \\ x_{2} = \frac{7 + \sqrt{61} }{2}$