InterviewSolution
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InterviewSolution
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Suppose `A=[{:(a,b),(c,d):}]` is real matrix with nonzero entries, ad-bc=0 , and `A^(2)`=A. Then a+d equalsA. 1B. 2C. 3D. 4 |
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Answer» Correct Answer - A `A^(2)=[{:(a,b),(c,d):}][{:(a,d),(c,d):}] ad =bc implies (a)/(b)=(c)/(d)=k` `=[{:(a^(2)+bc,ab+bd),(ac+cd,bc+d^(2)):}] a=bk,c=dk` `a^(2)+bc=a ,b(a+d)=b` `impliesa+d=1` |
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