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Grade 12th passAlgebra

if A&B are two square matrices such that B= -A-1BA, then prove that ( A+B)2=A2+B2

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Profile image of shreyansh
8 Years agoGrade 12th pass
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2 Answers

Profile image of Amit Sharma
ApprovedApproved Tutor Answer8 Years ago
It  is given that   
                                B = -A-1BA
           now, pre-multiplying by A on both sides, we will get
                                 AB = -BA
                                AB+BA = 0.........................(1)
Now coming to the problem:
(A+B)2=(A+B)*(A+B)  =  A2+B2+AB+BA.....................(2)
from (1) and (2), we get
(A+B)2=(A+B)*(A+B)
 
Profile image of Amit Sharma
8 Years ago
 
 
It  is given that   
                                B = -A-1BA
           now, pre-multiplying by A on both sides, we will get
                                 AB = -BA
                                AB+BA = 0.........................(1)
Now coming to the problem:
(A+B)2=(A+B)*(A+B)  =  A2+B2+AB+BA.....................(2)
from (1) and (2), we get
( A+B)2=A2+B2 as AB+BA =0 {from (1)}