問兩題十字交乘問題(詳細解法 1.xy^2+2xy-3x-y 2.(x+y)(x+y-3)+2 感恩!!!!!?

2015-12-15 2:07 pm

回答 (3)

2015-12-16 4:22 am
✔ 最佳答案
相信第一題的題目應該是
(1) xy² + 2xy - 3x - y + 1
=xy² + (2x-1)y - (3x-1)
=(y - 1)[xy + (3x-1)]
=(y - 1)(xy + 3x - 1)

(2) (x + y)(x + y - 3) + 2
=(x + y)² - 3(x + y) + 2
=[(x + y) - 1][(x + y) - 2]
=(x + y - 1)(x + y - 2)
2015-12-15 3:09 pm
第一題題目應該有誤
xy^2+2xy-3x-y=xy^2+2xy-2x-x-y+1-1=(xy^2-x)+(2xy-2x)-(y-1)-1
=x(y-1)(y+1)+2x(y-1)-(y-1)-1=(y-1)(xy+3x-1)-1 (分不完)

第二題
(x+y)(x+y-3)+2 =(x+y)[(x+y)-3]+2 =(x+y)^2 - 3(x+y)+2
=[(x+y)-2 ][(x+y)-1]=(x+y-2)(x+y-1)
2015-12-17 3:26 pm
不好意思評分給錯!!在此至上十萬分的歉意!


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