| A | x2-5x+6=x(x-5)+6 |
| B | x2-5x+6=(x-2)(x-3) |
| C | (x-2)(x-3)=x2-5x+6 |
| D | x2-5x+6=x(x-2)-3(x-2) |
| A | 2x-2y与y-x |
| B | x2-xy与xy-y2 |
| C | 3x+y与x+3y |
| D | 2x+10y与-2y |
| A | 42 |
| B | -42 |
| C | 13 |
| D | -13 |
| A | 2x2-xy-x=2x(x-y-1) |
| B | -xy2+2xy-3y=-y(xy-2x-3) |
| C | x(x-y)-y(x-y)=(x-y)2 |
| D | x2-x-3=x(x-1)-3 |
| A | -210 |
| B | -211 |
| C | 210 |
| D | -2 |