Х(х-6)+20х^2=7х-2 помогите плиз

x ( x - 6) + 20x² = 7x - 2 x² -6x + 20x² = 7x - 2 21x² - 13x + 2 = 0 D = b² - 4ac = 169 - 4 ×21×2 = 169 - 168 = 1 x1 =( 13 + 1) / 42 = 14/42 = 2/6 = 1/3 x2 = ( 13 - 1) 42 = 12/42 = 2/7