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Given A = [22-4-42-42-15], B = [1-10234012], find BA and use this to solve the system of equations y + 2z = 7, x – y = 3, 2x + 3y + 4z = 17. - Mathematics

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प्रश्न

Given A = `[(2, 2, -4),(-4, 2, -4),(2, -1, 5)]`, B = `[(1, -1, 0),(2, 3, 4),(0, 1, 2)]`, find BA and use this to solve the system of equations y + 2z = 7, x – y = 3, 2x + 3y + 4z = 17.

योग
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उत्तर

We have, A = `[(2, 2, -4),(-4, 2, -4),(2, -1, 5)]` and B = `[(1, -1, 0),(2, 3, 4),(0, 1, 2)]`

∴ BA = `[(1, -1, 0),(2, 3, 4),(0, 1, 2)] [(2, 2, -4),(-4, 2, -4),(2, -1, 5)]`

= `[(6, 0, 0),(0, 6, 0),(0, 0, 6)]`

= 6I

∴ B–1 = `"A"/6 = 1/6 [(2, 2, -4),(-4, 2, -4),(2,  -1, 5)]`  ....(i)

Given system of equation is:

x – y = 3

2x + 3y + 4z = 17

And y + 2z = 7

or `[(1, -1, 0),(2, 3, 4),(0, 1, 2)] [(x),(y),(z)] = [(3),(17),(7)]`

∴ `[(x),(y),(z)] = [(1, -1, 0),(2, 3, 4),(0, 1, 2)]^-1 [(3),(17),(7)]`

= `1/6 [(2, 2, -4),(-4, 2, -4),(2, -1, 5)] [(3),(17),(7)]`

= `1/16 [(6 + 34 - 28),(-12 + 34 - 28),(6 - 17 + 35)]`

= `1/6 [(12),(-6),(24)]`

= `[(2),(-1),(4)]`

∴ x = 2, y = –1 and z = 4

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अध्याय 4: Determinants - Exercise [पृष्ठ ७९]

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एनसीईआरटी एक्झांप्लर Mathematics [English] Class 12
अध्याय 4 Determinants
Exercise | Q 20 | पृष्ठ ७९

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