已知y-2x=0.求代数式(x^2-y^2)(x^2-xy+y^2)/(x^2+xy+y^2)(x^2-y^2).
问题描述：
已知y-2x=0.求代数式(x^2-y^2)(x^2-xy+y^2)/(x^2+xy+y^2)(x^2-y^2).
答
y-2x=0
y=2x
(x^2-y^2)(x^2-xy+y^2)/(x^2+xy+y^2)(x^2-y^2).
=(x^2-y^2)^2[(x^2+y^2)^2-(xy)^2]
=(x^2-(2x)^2)^2 [(x^2+(2x)^2)^2-(2x^2)^2]
=9x^4[25x^4-4x^4]
=189x^4
答
Y-2X=0
X,Y不等于0
Y=2X,Y/X=2,X/Y=1/2
y/x+x/y=5/2
(x^2-y^2)(x^2-xy+y^2)/(x^2+xy+y^2)(x^2-y^2).
=(x^2-xy+y^2)/(x^2+xy+y^2)
=(x/y-1+y/x)/(x/y+1/y/x)
=(5/2-1)/(5/2+1)
=3/7
答
y-2x=0
y=2x
(x^2-y^2)(x^2-xy+y^2)/(x^2+xy+y^2)(x^2-y^2).
=(x^2-xy+y^2)/(x^2+xy+y^2)
=(x^2-2x^2+4x^2)/(x^2+2x^2+4x^2)
=3x^2/7x^2
=3/7