array

Question

Q. A p×p array ‘M’ is defined as follows:-

M[a, b] = a – b for all a,b, 1 ≤ a, b ≤ p.      

The sum of elements of the array M is

(a) p – 1                                                                       (b) p² – 3p + 2

(c) 0                                                                             (d) p²(p+1)/ 2

Answer 1

To solve these type of question,,,take one example

let take 3×3 array

so M[1,1] =0

 M[1,2] =-1

M[1,3] =-2

M[2,1] =1

M[2,2] =0

M[2,3] =-1

M[3,1] =2

M[3,2] =1

M[3,3] =0

here we get sum of elements of the array M =0

and check option (put p=3)

so (c) is correct

Comments

Very good alternative way to tackle questions like this!

Answer 2

The answer for the above questions is C

take any simple matrix

and form the matrix with the help of given condition

and sum them all

you will get 0