(x-5)(2x+1)-2x(x-7)=1-x² розвязати ривняння

( x - 5)(2x + 1) - 2x( x - 7) = 1 - x^2
2x^2 - 9x - 5 - 2x^2 + 14x - 1 + x^2 = 0
x^2 + 5x - 6 = 0
D = b^2 - 4ac = 25 + 24 = 49 = 7^2
x1 = ( - 5 + 7) / 2 = 1
x2 = ( - 5 - 7) / 2 = - 6