What is the maximum number of different elements required to form a symmetric matrix of order 12?
Answer & explanation
Correct answer: option 3
Matrix of order 12 require 12 × 12 = 144 elements.
12 elements for $i=j$
$\frac{144-12}{2}=66$ elements for $i<j$
∴ Maximum number of different elements required are $66+12=78$