x2+6x-27=0
x2-5x-6=0
x1 = -1, x2 = 6
x1 = 2, x2 = 7
x1 = 3, x2 = -9
x2+7x+12=0
x2+x-20=0
x2-9x+14=0
x1 = -5, x2 = 4
x1 = 4, x2 = 6
x2-10x+24=0
x1 = -3, x2 = -4
