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If `A = [(5a,-b),(3,2)]`and `A adj A=AA^T`, then `5a+b`is equal to:A. 5B. 4C. 13D. `-1` |
Answer» Correct Answer - A A adj `A=A A^(T)` `implies |A|I=A A^(T)` `implies (10a+3b) [(1,0),(0,1)]=[(5a,-b),(3,2)][(5a,3),(-b,2)]` `implies 25a^(2)+b^(2)=10a+3b, 15a-2b=0, 10a+3b=13` `implies 10a+(3.15a)/2=13` `implies 65a=2xx13` `implies a=2/5` `implies 5a=2` `implies 2b=6` `implies b=3` `:. 5a+b=5` |
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