2 votes 2 votes Coefficient of is ?? Combinatory combinatory + – Ravi_1511 asked Aug 7, 2016 retagged Jun 27, 2017 by Arjun Ravi_1511 309 views answer comment Share Follow See all 0 reply Please log in or register to add a comment.
Best answer 2 votes 2 votes =x^20(1+x+x^2+....)^4 =x^20 ( 1/(1-x)^4) = x^20 (1-x)^-4 So equation is (n+k-1)Cn We need x^30 ...we have x^20 .. So n=30-20=10 k =4 So ans = (10+4-1 )C 10 = 286 papesh answered Aug 7, 2016 selected Sep 24, 2016 by papesh papesh comment Share Follow See all 0 reply Please log in or register to add a comment.