1.

माना `A=[(2,3),(-1,2)]` और `f(x)=x^(2)-4x+7` दर्शाइए कि `f(A)=O` तथा इसके प्रयोग से `A^(5)` ज्ञात कीजिए।

Answer» `f(x)=x^(2)-4x+7`
`:.f(A)=A^(2)-4A+7I` जहां `I=[(1,0),(0,1)]`
अब `A^(2)=A.A=[(2,3),(-1,2)][(2,3),(-1,2)]`
`=[(4-3,6+6),(-2-2,-3+4)[=[(1,12),(-4,1)]`
`-4A=[(-8,-12),(4,-8)]` और `7I=[(7,0),(0,7)]`
`:.f(A)=A^(2)-4A+7I`
`impliesf(A)=[(1,12),(-4,1)]+[(-8,-12),(4,-8)]+[(7,0),(0,7)]`
`impliesf(A)=[(1-8+7,12-12+0),(-4+4+0,1-8+7)]`
`=[(0,0),(0,0)]=O`
अब `f(a)=O`
`impliesA^(2)-4A+7I=O`
`impliesA^(2)-4A-7I`………..i
`impliesA^(3)=A^(2)A=(4A-7I)A=4A^(2)-7IA`
`impliesA^(3)=4(4A-7I)-7A`[समी 1 से]
`implies A^(3)=9A-28I`
`impliesA^(4)=9A^(2)-28AI`
`=9(4A-7I)-28AI` [समी 1 से]
`impliesA^(5)=36A-63I-28A=8A-63I`
`impliesA^(5)=A^(4)A=(8A-63I)A=8A^(2)-63IA`
`implies A^(5)=8(4A-8I)-63A=-31A-56I`
[समी 1 से]
`impliesA^(5)=-31[(2,3),(-1,2)]-56[(1,0),(0,1)]`
`=[(-62,-93),(31,-62)]+[(-56,0),(0,-56)]=[(-118,-93),(31,-118)]`


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