方程式問題(要中間的步驟) 20點

xy(x+3y)+x(1-y)-x
=x(y[x+3y]+(1)(1-y)-1]
=x(xy+3y^2+1-y-1)
=x(xy+3y^2-y)
=xy(x+3y-1)

2009-10-01 15:42:05 補充：
仲未教到抽未知數?

2009-10-01 15:56:32 補充：
尾3果到可不乘入去
=x[y(x+3y)+1-y-1]
再抽y
=xy[(x+3y)-1]
=xy(x+3y-1)

2009-10-04 20:49:43 補充：
尾3果到可不乘y入去
=x(y[x+3y]+1-y-1)
=x(y[x+3y]-y)
=xy(x+3y-1)

xy(x+3y)+x(1-y)-x
= x[y(x+3y)+(1-y)-1]
=x(xy+3y^2+1-y-1)
=x(3y^2+xy-y)
=xy(3y+x-1)

xy(x+3y)+x(1-y)-x
=x2次y+3xy2次+x-xy-x
=xy(x+3y-1)

P.S:答案係將第一個步驟大家都有的xy抽出黎，放企括號出面，其他個d就放企括號入面。