lf the term independent of x in the expansion of 32x2−13x9is k, then 18k is equal to

given binomial is 32x2−13x9So the general term,Tr+1=9Cr32x29−r−13xr=9Cr329−r−13rx18−3rlf the term is independent of x, then 18−3r=0⇒r=6∴(r+1) th  term =7th term is independent of xNow, as T6+1=k⇒ 9C6323−136=k⇒ 9×8×73×2×127×8=k⇒k=718⇒18k=7Hence, option (b) is correct.