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1)

Matrix A=[123115247], then   the value of a31A31+a32A32+a33A33 is 


A) 1

B) 13

C) -1

D) -13

Answer:

Option C

Explanation:

 We have

   A=[123115247]

 a31=2, a32=4, a33= 7

 and   A31=[2315]=103=7

 A32=[1315]=(53)=2

A33=[1211]=12=1

    a31A31+a32A32+a33A33

  = 2(7)+4(-2)+7(-1)

   =14-8-7=-1