x²-4x-9=0x²-4x+4-13=0(x-2)²=13x-2=±√13x=±√13+2∴x1=√13+2,x2=2-√13x²+6x-2=0x²+6x+9-11=0(x+3)²=11x+3=±√11x=±√11-3∴x1=√11-3,x2=-√11-3