X^2-8x+15=0
X^2+12x+20=0
X^2-5x-6=0
X^2-8x-9=0
Найдите корни уравнения

$x^2 - 8x + 15 = 0 left { {{x1+x2 = -p} atop {x1*x2 = q}} right. left { {{x1+x2 = 8} atop {x1*x2 = 15}} right. left { {{x1 = 5} atop {x2 = 3}} right.$

$x^2 + 12x + 20 = 0 D = 64 x1 = - 2 ; x2 = - 10$

$x^2 - 5x - 6 = 0 left { {{x1+x2 = -p} atop {x1*x2 = q}} right. left { {{x1+x2 = 5} atop {x1*x2 = -6}} right. left { {{x1 = 6} atop {x2 = -1}} right.$

$x^2 - 8x - 9 = 0 D = 100 x1 = 9 ; x2 = -1$