x²-2x-3=0 x²-2x=3x²-2x+1=4(x-1)²=4x-1=±2x=1±2x=3或-1
x²+8x+12=0x²+8x+16=4(x+4)²=4x+4=±2x=-4±2x=-6或x=-2
2(X-3)=3X(X-3)3X(X-3)- 2(X-3)=0(3X-2)(X-3)=0x=2/3,或者x=3
x²-5x-24=0
(x-8)(x+3)=0x=8或x=-3
1,(X~3)(x+1) =0