由于1>1/√2>1/√3>……>1/√2010,
1+1/√2+1/√3+……+1/√2010>2010*1/√2010=√2010
分母有理化,得x=3+2√2,y=3-2√2
所以x/y=(3+2√2)^2,y/x=(3-2√2)^2,
x/y+y/x-4=2*(9+8)-4=30
√2010=2010/√2010
=1/√2010+1/√2010+1/√2010+……+1/√2010(共2010个)
1/√2010<1
1/√2010<1/√2
1/√2010<1/√3
1/√2010<1//√4
……
1/√2010<1/√2009
1/√2010=1/√2010
1+1/√2+1/√3+……+1/√2010>√2010
x/y=(3+2√2)/(3-2√2)
(上下同乘3+2√2)
=(3+2√2)²/(3²-(2√2)²)
=(9+6√2+8)
=17+6√2
y/x=1=(3-2√2)/(3+2√2)
(上下同乘3-2√2)
=(3-2√2)²/(3²-(2√2)²
=(9-6√2+8)
=17-6√2
x/y+y/x-4=17+6√2+17-6√2-4=30