x^2 + 17x - 18 = x^2 - 1 +17x - 17 = (x-1)(x+1)+17(x-1) = (x-1)(x+1+17 )= (x-1)(x+18)
5x^2 - 13x - 6 = 5*(x+0,4)(x-3) = (5x+2)(x-3)
Решим квадратное уравнение 5x^2 - 13x - 6 = 0,
D = (-13)^2 - 4*5*(-6) = 169 + 120 = 189 = 17^2, x1 =(13-17)/10 = - 0,4; x2 = (13+17)/10 = 3
x^2 + 17x - 18 = x^2 - 1 +17x - 17 = (x-1)(x+1)+17(x-1) = (x-1)(x+1+17 )= (x-1)(x+18)
5x^2 - 13x - 6 = 5*(x+0,4)(x-3) = (5x+2)(x-3)
Решим квадратное уравнение 5x^2 - 13x - 6 = 0,
D = (-13)^2 - 4*5*(-6) = 169 + 120 = 189 = 17^2, x1 =(13-17)/10 = - 0,4; x2 = (13+17)/10 = 3