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If `A`is an idempotent matrix satisfying, `(I-0. 4 A)^(-1)=I-alphaA ,w h e r eI`is the unit matrix of the name order as that of `A ,`then th value of `|9alpha|`is equal to ________. |
Answer» Correct Answer - 6 Given `A^(2)=A` Now `I=(I-0.4A) (I-alphaA)` `=I-IalphaA-0.4 AI+0.4 alpha A^(2)` `=I-Aalpha-0.4A+0.4 alpha A` `= I-A(0.4+alpha) + 0.4 alpha A` `implies 0.4 alpha=0.4+alpha` `implies alpha=-2//3` `implies |9alpha|=6` |
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