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Easy problem , just a mixture of many famous problems , try solving tk check your concepts in different topics
Repost from Hemlo's Questions JEE PCM Collection (Comeback)
For trace i=j, for inverse just keep track of diagonal elements for a triangular matrix , if diagonal elements are a,b,c in inverse they become 1/a,1/b,1/c so aii=diagonal element= 1/2i^2 becomes 2i^2 in A^-1 , so we need to sum 2i^2 , for i=1 to n , that comes to
n(n+1)(2n+1)/3 , now sum this for n=1 to 5 , ie becomes 2+ 10+28+60+110= 210 --> final answer =210/10=21 , just oral but no one answered
Repost from Hemlo's Questions JEE PCM Collection (Comeback)
Old goated limit , let's see how many can solve , btw it's easy
Maybe this inequality will come into play in some questions so just posting here so that maybe you can use it directly...
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