Question

初二数学先化简再求值，要过程哦～①

必须要过程诺，

Answer 1

原式={[(X+Y)+(X-Y)]/(X+Y)(X-Y)}/[2X/(X^2-2XY+Y^2)]
=[2X/(X+Y)(X-Y)]*(X-Y)^2/2X
=X+Y
=根号2+1

Answer 2

[1/(x-y)+1/(x+y)]/[2x/(x^2-2xy+y^2)]=(x+y+x-y)/[(x-y)(x+y)]*(x-y)^2/2x=2x/[(x-y)(x+y)]*(x-y)^2/2x
=(x-y)/(x+y)=x^2-y^2=2-1=1

Answer 3

原式=（X+Y+X-Y）·（X-Y）^2/[（x+y）（x-y）·2x]=（x-y）/（x+y）=3-2根号2