约分.（1）a-1/a+1=___ （2）m^2-4mn+4n^2/m^2+4mn+4n^2=____（3）x^2-y^2/x+y_数学解答

约分.（1）a-1/a+1=___ （2）m^2-4mn+4n^2/m^2+4mn+4n^2=____
（3）x^2-y^2/x+y=____ （4）x^2+y^2+2xy/x^2-y^2=____

人气：345 ℃　时间：2020-06-25 13:53:12

解答

（1）(a-1)/(a+1)= (a-1)/(a+1)
（2）(m^2-4mn+4n^2)/(m^2+4mn+4n^2)
= (m-2n)^2/(m+2n)^2
（3）(x^2-y^2)/(x+y)
= (x-y)(x+y)/(x+y)
= x-y
（4）(x^2+y^2+2xy)/(x^2-y^2)
=(x+y)^2/[(x+y)(x-y)]
=(x+y)/(x-y)