x (x-6)+20x2=7X-2
решите уровнение

x(x-6)+20x^2 = 7x - 2x^2 - 6x + 20x^2 -7x + 2 = 021x^2 -13x + 2 = 0D = (-13)^2 - 4*2*21 = 169 - 168 = 1√1 = 1x_1 = (13+1)/42 = 14/42 = 1/3x_2 = (13-1)/42 = 12/42 = 2/7 

2х-6х+20х-7х=-2-29х=-4х=9:(-4)х=-2,25