x²-3x=15x²-3x-15=0x1=3/2+(9/4+15)^0.5=3/2+(69/4)^0.5=(3+69^0.5)/2x2=3/2-(9/4+15)^0.5=3/2-(69/4)^0.5=(3-69^0.5)/2x²+px+q=0x1=-p/2+((p/2)^2-q)^2x2=-p/2-((p/2)^2-q)^2