Question 761834
{{{(x+1/x)^20}}}......multiply to expend

{{{(x+1/x)(x+1/x)(x+1/x)(x+1/x)(x+1/x)(x+1/x)(x+1/x)(x+1/x)(x+1/x)(x+1/x)(x+1/x)(x+1/x)(x+1/x)(x+1/x)(x+1/x)(x+1/x)(x+1/x)(x+1/x)(x+1/x)(x+1/x)}}}

{{{x^20+1/x^20+20 x^18+20/x^18+190 x^16+190/x^16+1140 x^14+1140/x^14+4845 x^12+4845/x^12+15504 x^10+15504/x^10+38760 x^8+38760/x^8+77520 x^6+77520/x^6+125970 x^4+125970/x^4+167960 x^2+167960/x^2+184756}}}

so, the coefficient of {{{x^2}}} is {{{167960}}}