Question

已知x的平方-4xy+4y的平方=0，那么x+y除以x-y

Answer 1

将x的平方-4xy+4y的平方=0简化为（x-2y）的平方=0
得出x-2y=0
即 x=2y
代入x+y除以x-y，答案为3

Answer 2

把x的平方-4xy+4y的平方=0配方得x的平方减2y的平方=0
x的平方=2y的平方，所以x=+-根号2y，于是x+y=（1+-根号2）y，x-y=(1-+根号2）y
故x+y除以x-y=-3-2倍根号2或2倍根号2-3

Answer 3

x2-4xy+4y2=o
{x-2y}2=0
x=2y
x=2y x+y=3y x-y=y
所以商3

Answer 4

解得x=2y代入x+y/x-y得3y/y=3

Answer 5

-(y-1)/(y+1) 可以么？
16x^2y^2+16y^2-32xy^2
=x^2y^2+y^2(1-2x)
=(x^2+1-2x)y^2=0
x^2-2x+1=0
x=1
(x+y)/(x-y)=(x+y)^2/x^2-y^2=(1+y^2-2y)/1-y^2=(y-i)^2/-(y+1)(y-1)=-(y-1)/(y+1)