0 votes 0 votes I solved it by taking matrix ,I am confused in commutative Set Theory & Algebra zeal test-series + – Prince Sindhiya asked Nov 17, 2018 reopened Jul 11, 2022 by Arjun Prince Sindhiya 537 views answer comment Share Follow See all 6 Comments See all 6 6 Comments reply Show 3 previous comments Prince Sindhiya commented Nov 19, 2018 reply Follow Share https://gateoverflow.in/87051/gate1989-1-v 0 votes 0 votes Prince Sindhiya commented Nov 19, 2018 reply Follow Share See this 0 votes 0 votes Shaik Masthan commented Nov 19, 2018 reply Follow Share then close your question 1 votes 1 votes Please log in or register to add a comment.
1 votes 1 votes Total no of elements = $n^2$ no of diagonal elements = n so total no of non diagonal elements = $n^2$ - $n$ half of them will be commutative to other half=> ($n^2$ - $n$ $)/$$ 2 $ option b? Hemanth_13 answered Nov 17, 2018 Hemanth_13 comment Share Follow See 1 comment See all 1 1 comment reply Magma commented Nov 19, 2018 reply Follow Share You can also include diagonal elements from set S S = { 1,2,3.....N} 1*1 = 1*1 2*2 = 2*2 .. N*N = N*N N + (N 2 - N) /2 = N 2 + 1 / 2 0 votes 0 votes Please log in or register to add a comment.