If A is a symmetric matrix and B is skew- symmetric matrix such that   A + B = 2 3 5 - 1 , then A B is…

If A is a symmetric matrix and B is skew- symmetric matrix such that  A+B=235-1 , then AB is equal to:
  1. -4214 
  2. 4-21-4
  3. 4-2-1-4
  4. -4-2-14

Solution

Given A is symmetric and B is skew symmetric, hence 
A=abbc and B=0d-d0
Now A+B=ab+db-dc=235-1
a=2,  b=4,  c=-1 and d=-1
A=244-1 and B=0-110
Hence AB=244-10-110=4-2-1-4

Asked in: JEE Main 2019 (12 Apr Shift 1)

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