(1)
n/m=3/5
m/(m+n)+m/(m-n)-m^2/(m^2-n^2)
=m^2-mn+m^2+mn-m^2/(m^2-n^2)
=m^2/(m^2-n^2)
=1/[1-(n/m)^2]
=1/[1-(3/5)^2]
=25/16
(2)
(x+1)(x-1)/(x+1)=0
x-1=0
x=1
(3)[(1+1/x)/(x^2-1/x)]^-1
=(x^3-1)/(x+1)
1/(x+1)=1/(√2+1)=√2-1
x^3-1=2√2-1
[(1+1/x)/(x^2-1/x)]^-1
=(2√2-1)(√2-1)
=5-3√2
(1+1/x)/(x^2-1/x)]
=1/(5-3√2)
=(5+3√2)/7
怀疑分子是1-1/x?
(4)(x^2-4)/(x-2)
=(x+2)(x-2)/(x-2)
=x+2=0
x=-2