矩形的周长是28CM
则x+y=28/2=14
X³+X²Y-XY²-Y³=0
(x^3 -y^3)+(x^2y-xy^2)=0
(x-y)(x^2+xy+y^2)+xy(x-y)=0
(x-y)(x^2+2xy+y^2)=0
(x-y)(x+y)^2=0
所以x=y
即x=y=7
矩形的面积 =xy=7*7=49 cm^2
矩形的周长是28CM
则x+y=28/2=14
X³+X²Y-XY²-Y³=0
(x^3 -y^3)+(x^2y-xy^2)=0
(x-y)(x^2+xy+y^2)+xy(x-y)=0
(x-y)(x^2+2xy+y^2)=0
(x-y)(x+y)^2=0
所以x=y
即x=y=7
矩形的面积 =xy=7*7=49 cm^2