matrices (which one is symmetric)?

Question

i would like to find out which one of the following matrices is symmetric

-7 -8 5
9 7 9
5 -8 6



5 9 -7
-8 7 9
6 -8 5



6 9 5
9 7 -8
5 -8 -7

Any help would be greatly appreciated

they are all 3 by 3 matrices

Answer 1

An easier way, without all the jargon, is if you flip every entry across the main diagonal, you get the same matrix back. By this def, the third one is symmetric.

Answer 2

The third one.

A matrix 'N' is symmetric if the elements N(a,b) = N(b,a) for all values 'a' and 'b'

i.e. N(1,2) = N(2,1)

If you look at the 3rd matrix, N(1,2) = N(2,1) = 9; N(1,3)=N(3,1) = 5; N(3,2) = N(2,3) = -8

Answer 3

Only the last one is symmetric. A matrix A is symmetric if A_i,j = A_j,i for all indices i and j.