{(x-2y)(x-y)+(x²高巧-y²)-(-x-y)²}÷5x=
{(x-2y)(x-y)+[(x-y)-(x+y)]*(x+y)}÷5x=
{(饥念哪x-2y)(x-y)-2y*(x+y)}÷5x=
{(x²烂码-3xy+2y²)-2xy-y²)}÷5x=
(x²-5xy)÷5x=
x(x-5y)÷5x=
(x-5y)÷5=
5÷5=1
{(x-2y)(x-y)+(x²-y²)-(-x-y)²}÷5x=
{(颂纤氏x-2y)(x-y)+[(x-y)-(x+y)]*(x+y)}÷5x=
{(竖亩x-2y)(x-y)-2y*(x+y)}÷5x=
{(野散x²-3xy+2y²)-2xy-y²)}÷5x=
(x²-5xy)÷5x=
x-5y=
5
先将大括号内后两项提取提取公因式(x+y),再就好做了!
答案:1
因液派则为x-5y=5,所以x=5y+5
代入
{(x-2y)(x-y)+(x²-y²闹棚)-(-x-y)²}÷5x
={(3y+5)(4y+5)-2y(y+5)-2y^2}/5(5y+5)
=(12y^2+35y+25-10y^2-10y-2y^2)/25(y+1)
=(25y+25)/羡含25(y+1)
=25(y+1)/25(y+1)
=1
1