問題詳情:
把多項式x2-y2-2x-4y-3因式分解之後,正確的結果是[ ]
A.(x+y+3)(x-y-1). B.(x+y-1)(x-y+3)
C.(x+y-3)(x-y+1). D.(x+y+1)(x-y-3)
【回答】
D
x2-y2-2x-4y-3
=(x2-2x+1)-(y2+4y+4)
=(x-1)2-(y+2)2
=[(x-1)+(y+2)][(x-1)(y+2)]
=(x+y+1)(x-y-3),
∴ 選(D).
知識點:數學競賽
題型:選擇題
問題詳情:
把多項式x2-y2-2x-4y-3因式分解之後,正確的結果是[ ]
A.(x+y+3)(x-y-1). B.(x+y-1)(x-y+3)
C.(x+y-3)(x-y+1). D.(x+y+1)(x-y-3)
【回答】
D
x2-y2-2x-4y-3
=(x2-2x+1)-(y2+4y+4)
=(x-1)2-(y+2)2
=[(x-1)+(y+2)][(x-1)(y+2)]
=(x+y+1)(x-y-3),
∴ 選(D).
知識點:數學競賽
題型:選擇題