解
是x=√2+1/(√2-1)吗?
xy=(√2+1)/(√2-1)×(√2-1)/(√2+1)=1
x²+y²=(√2+1)²/(√2-1)²+(√2-1)²/(√2+1)²
=(3+2√2)/(3-2√2)+(3-2√2)/(3+2√2)
=[(3+2√2)²-(3-2√2)²]/(3-2√2)(3+2√2)
=(12√2+12√2)/(9-8)
=24√2
y/x+x/y
=(y²+x²)/xy
=24√2