решите уравнение a) 12x^2+36x=0 б) 2x^2-7x-15=0

a) 12x^2+36x=012x(x+3) = 012x = 0x = 0 и x + 3 = 0x = -3Ответ : 0; -3б) 2x^2 - 7x - 15 = 0 Штучный способ :2x^2/2 - 7x - 15*2 = 0x -> aa^2 - 7a - 30 = 0a1 = 10a2 = -3x1 = 10/2 = 5;x2 = -3/2 = -1,5 Ответ : 5; -1,5;Через дискриминант : 2x^2 - 7x - 15 = 0a=2; b=-7; c=-15D = b^2 - 4ac = (-7)^2 - 4 * 2 * (-15) = 49 + 120 = 169 = 13^2D>0x1 = -b + √D/2a = 7 + 13/2*2 = 20/4 = 5;x2 = -b - √D/2a = 7 - 13/2*2 = -6/4 = -3/2 = -1,5; Ответ : 5; -1,5;