(2-1)/(x-1)÷(x+1-3/(x-3)
=1/(x-1)÷(x²-2x-3-3)/(x-3)
=1/(x-1)÷(x²-2x-6)/(x-3)
=(x-3)/(x-1)(x²-2x-6)
2/(x-2)=1/(x²-4)
2x²-8=x-2
2x²+x-6=0
(2x-3)(x+2)=0
2x-3=0 x+2=0
∴x=2/3或x=-2
1/(x-2)=2+1/(2-x)
1=2x-4-1
2x=6
x=3
[1/（x-y)-1/(x+y)]*(x²-y²)/xy x=-1 y=3
=(x+y-x+y)/(x²-y²)*(x²-y²)/xy
=2xy²
=2*(-1)*3²
=-18
已知x√2-1 y=√2+1 求x/y+y/x
x/y+y/x
=(x²+y²)/xy
=[(√2-1)²+(√2+1)²](√2-1)(√2+1)
=(2-2√2+1+2+2√2+1)/(2-1)
=6