Question

进来看看当X=?时,分式2X-1/3-5X的值为-1已知X^2-3Y^2=2XY,X>0,Y>0,求X+2Y/X-Y的值

Answer 1

1、x=2/3

2、1/2

第2题做法：x^2-3y^2-y^2=2xy-y^2

(x+2y)(x-2y)=y(2x-y)

x+2y=y

x^2-3y^2+2y^2=2xy+2y^2

(x+y)(x-y)=2y(x+y)

x-y=2y

X+2Y/X-Y=y/2y=1/2

第1题那个太简单了.