Question

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18. If A =
then verify the truth of the following.
1 0
0 1
(1) (A + B) = A + B +2AB
(ii) (A + B)(A-B) = A2-B2
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Answer 1

1. (a+b)2 = a(a+b) + b(a+b)

= a2 + ab + ab +b2

= a2 + b2+ 2ab

2. (a+b)(a-b) = a(a-b) + b(a-b)

= a2 - ab + ab - b2

= a2-b2