因为1+x^2=1+(1/4)·[5^(1/n)-5^(-1/,n)]^2=1+(1/4)·[5^(2/n)-2+5^(-2/,n)]=(1/4)·[5^(1/n)+2+5^(-1/,n)]=(1/4)·[5^(1/n)+5^(-1/,n)]^2,于是x+根号(1+x^2)=(1/2)·[5^(1/n)-5^(-1/,n)]+1+(1/2)·[5^(1/n)+5^(-1/,n)]=5^(1/n),所以,原式=5.
如图