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Solve the system of linear equations using the matrix method. 2x – y = –2 3x + 4y = 3 - Mathematics

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प्रश्न

Solve the system of linear equations using the matrix method.

2x – y = –2

3x + 4y = 3

बेरीज
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उत्तर

Given system of equations,

2x – y = –2
3x + 4y = 3

The system of equations can be written as AX = B. Hence, X = A−1B.

A = `[(2,-1),(3,4)]`, X = `[(x),(y)]` and B = `[(-2),(3)]`

⇒ |A| = `|(2,-1),(3,4)|`

= 8 + 3

= 11 ≠ 0

The cofactors of the elements of matrix A are as follows:

A11 = (−1)1+1 (4) = 4

A12 = (−1)1+2 (3) = −3

A21 = (−1)2+1 (−1) = 1

A22 = (−1)2+2 (2) = 2

Matrix made of elements of cofactor of A = `[(4,-3),(1,2)]`

adj A = `[(4,-3),(1,2)] = [(4,1),(-3,2)]`

A−1 = `1/|A|` (adj A)

= `1/11 [(4,1),(-3,2)]`

∴ X = A−1B

= `1/11 [(4,1),(-3,2)] [(-2),(3)]`

= `1/11 [(-8 + 3),(6 + 6)]`

= `1/11 [(-5),(12)]`

= `[(-5/11),(12/11)]`

⇒ `[(x),(y)] = [(-5/11),(12/11)]`

⇒ x = `-5/11` and y = `12/11`

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पाठ 4: Determinants - Exercise 4.6 [पृष्ठ १३६]

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एनसीईआरटी Mathematics Part 1 and 2 [English] Class 12
पाठ 4 Determinants
Exercise 4.6 | Q 8 | पृष्ठ १३६

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