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यदि `A^(-1)=[(3,-1,1),(-15,6,-15),(5,-2,2)]` और `B=[(1,2,-2),(-1,3,0),(0,-2,1)]` हो तो `(AB)^(-1)` का मान ज्ञात कीजिए । |
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Answer» `B=[(1,2,-2),(-1,3,0),(0,-2,1)]` `:.|B|=|(1,2,-2),(-1,3,0),(0,-2,1)|` `=1(3-0)-2(-1-0)-2(2-0)` `=3+2-4=1!=0` `B_(11)=3,B_(12)=1,B_(13)=2` `B_(21)=2,B_(22)=1,B_(23)=2` `=B_(31)=6,B_(32)=2,B_(33)=5` `impliesadjB=[(3,1,2),(2,1,2),(6,2,5)]=[(3,2,6),(1,1,2),(2,2,5)]` अब `B^(-1)=1/(|B|)adjB=[(3,2,6),(1,1,2),(2,2,6)]` दिया है `A^(-1)=[(3,-1,1),(-15,6,-5),(5,-2,2)]` `(AB)^(-1)=B^(-1)A^(-1)` `=[(3,2,6),(1,1,2),(2,2,5)][(3,-1,1),(-15,6,-5),(5,-2,2)]` `=[(9-30+30,-3+12-12,3-10+12),(3-15+10,-1+6-4,1-5+4),(6-30+25,-2+12-10,2-10+10)]` `=[(9,-3,5),(-2,1,0),(1,0,2)]` |
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