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Ex 4.5, 7 - Chapter 4 Class 12 Determinants
Last updated at August 17, 2026 by Teachoo
Find solution of equations- Equations given
Chapter 4 Class 12 Determinants
Concept wise
- Finding determinant of a 2x2 matrix
- Evalute determinant of a 3x3 matrix
- Area of triangle
- Equation of line using determinant
- Finding Minors and cofactors
- Evaluating determinant using minor and co-factor
- Find adjoint of a matrix
- Finding Inverse of a matrix
- Inverse of two matrices and verifying properties
- Finding inverse when Equation of matrice given
- Checking consistency of equations
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Find solution of equations- Equations given
- Find solution of equations- Statement given
- Verifying properties of a determinant
- Two rows or columns same
- Whole row/column zero
- Whole row/column one
- Making whole row/column one and simplifying
- Proving Determinant 1 = Determinant 2
- Solving by simplifying det.
- Using Property 5 (Determinant as sum of two or more determinants)
Transcript
Ex 4.5, 7 Solve system of linear equations, using matrix method. 5x+ 2y = 4 7x + 3y = 5 The system of equations is 5x + 2y = 4 7x + 3y = 5 Writing equation as AX = B [โ 8(5&2@7&3)] [โ 8(๐ฅ@๐ฆ)] = [โ 8(4@5)] Hence A = [โ 8(5&2@7&3)], X = [โ 8(๐ฅ@๐ฆ)] & B = [โ 8(4@5)] Calculating |A| |A| = |โ 8(5&2@7&3)| = 5(3) โ 7(2) = 15 โ 14 = 1 โ 0 Since |A|โ 0, System of equations is consistent & has a unique solution Now, AX = B Solution is X = A-1 B Calculating Aโ1 A-1 = 1/(|A|) adj (A) A = [โ 8(5&2@7&3)] adj A = [โ 8(5&2@7&3)] = [โ 8(3&โ2@โ7&5)] Now, A-1 = 1/(|A|) adj A Putting values = 1/1 [โ 8(3&โ2@โ7&5)] = [โ 8(3&โ2@โ7&5)] Now X = A-1 B [โ 8(๐ฅ@๐ฆ)] = [โ 8(3&โ2@โ7&5)] [โ 8(4@5)] [โ 8(๐ฅ@๐ฆ)] = [โ 8(3(4)+(โคถ7โ2)5@โ7(4)+5(5))] [โ 8(๐ฅ@๐ฆ)] = [โ 8(2@โ3)] Hence, x = 2 & y = โ3
