Question

Find the r^th term in the expansion of `(x + 1/x)^(2r)`

Answer 1

We have T_r = `""^(2r)"C"_(r - 1)   (x)^(2r - r + 1) (1/x)^(2r)`.

= `(2r)/((r - 1)(r + 1)) x^(r + 1 - r + 1)`

= `(2r)/((r - 1)(r + 1)) x^2`