(2x-1)(2x+1)-(x-3)(x+1)=18​

(2x-1)(2x+1)-(x-3)(x+1)=18

4x² - 1 - (x² + x - 3x - 3) - 18 = 0

4x² - 1 - (x² - 2x - 3) - 18 = 0

4x² - 1 - x² + 2x + 3 - 18 = 0

3x² + 2x - 16 = 0

a = 3; b = 2; c = -16

D = b²-4ac => 2²-4*3*(-16) = 4+12*16 = 196

√196 = 14

x = $\frac{-b+-\sqrt{D} }{2a}$

x₁ = $\frac{-2+14}{6} = 2$

x₂ = $\frac{-2-14}{6} = -\frac{8}{6} = -2\frac{2}{3}$

Ответ: x₁ = 2, x₂ = $-2\frac{2}{3}$

(2x-1)(2x+1)-(x-3)(x+1)=18