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If A=[(2,-1),(4,2)],B=[(4,3),(-2,1)] and...

If `A=[(2,-1),(4,2)],B=[(4,3),(-2,1)]` and `C=[(-2,-3),(-1,2)]`, find each of the following :
(i) `2B+3C`
(ii) `-2A+(B+C)`
(iii) `(2A-3B)-C`
(iv) `A+(2B-C)`
(v) `A+(B+C)`
(vi) `(A+B)+C`.

Text Solution

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The correct Answer is:
To solve the given problem, we will perform matrix operations step by step for each part of the question. Given matrices: - \( A = \begin{pmatrix} 2 & -1 \\ 4 & 2 \end{pmatrix} \) - \( B = \begin{pmatrix} 4 & 3 \\ -2 & 1 \end{pmatrix} \) - \( C = \begin{pmatrix} -2 & -3 \\ -1 & 2 \end{pmatrix} \) ### (i) Calculate \( 2B + 3C \) 1. **Calculate \( 2B \)**: \[ 2B = 2 \times \begin{pmatrix} 4 & 3 \\ -2 & 1 \end{pmatrix} = \begin{pmatrix} 8 & 6 \\ -4 & 2 \end{pmatrix} \] 2. **Calculate \( 3C \)**: \[ 3C = 3 \times \begin{pmatrix} -2 & -3 \\ -1 & 2 \end{pmatrix} = \begin{pmatrix} -6 & -9 \\ -3 & 6 \end{pmatrix} \] 3. **Add \( 2B \) and \( 3C \)**: \[ 2B + 3C = \begin{pmatrix} 8 & 6 \\ -4 & 2 \end{pmatrix} + \begin{pmatrix} -6 & -9 \\ -3 & 6 \end{pmatrix} = \begin{pmatrix} 8 - 6 & 6 - 9 \\ -4 - 3 & 2 + 6 \end{pmatrix} = \begin{pmatrix} 2 & -3 \\ -7 & 8 \end{pmatrix} \] ### (ii) Calculate \( -2A + (B + C) \) 1. **Calculate \( B + C \)**: \[ B + C = \begin{pmatrix} 4 & 3 \\ -2 & 1 \end{pmatrix} + \begin{pmatrix} -2 & -3 \\ -1 & 2 \end{pmatrix} = \begin{pmatrix} 4 - 2 & 3 - 3 \\ -2 - 1 & 1 + 2 \end{pmatrix} = \begin{pmatrix} 2 & 0 \\ -3 & 3 \end{pmatrix} \] 2. **Calculate \( -2A \)**: \[ -2A = -2 \times \begin{pmatrix} 2 & -1 \\ 4 & 2 \end{pmatrix} = \begin{pmatrix} -4 & 2 \\ -8 & -4 \end{pmatrix} \] 3. **Add \( -2A \) and \( (B + C) \)**: \[ -2A + (B + C) = \begin{pmatrix} -4 & 2 \\ -8 & -4 \end{pmatrix} + \begin{pmatrix} 2 & 0 \\ -3 & 3 \end{pmatrix} = \begin{pmatrix} -4 + 2 & 2 + 0 \\ -8 - 3 & -4 + 3 \end{pmatrix} = \begin{pmatrix} -2 & 2 \\ -11 & -1 \end{pmatrix} \] ### (iii) Calculate \( (2A - 3B) - C \) 1. **Calculate \( 2A \)**: \[ 2A = 2 \times \begin{pmatrix} 2 & -1 \\ 4 & 2 \end{pmatrix} = \begin{pmatrix} 4 & -2 \\ 8 & 4 \end{pmatrix} \] 2. **Calculate \( 3B \)**: \[ 3B = 3 \times \begin{pmatrix} 4 & 3 \\ -2 & 1 \end{pmatrix} = \begin{pmatrix} 12 & 9 \\ -6 & 3 \end{pmatrix} \] 3. **Calculate \( 2A - 3B \)**: \[ 2A - 3B = \begin{pmatrix} 4 & -2 \\ 8 & 4 \end{pmatrix} - \begin{pmatrix} 12 & 9 \\ -6 & 3 \end{pmatrix} = \begin{pmatrix} 4 - 12 & -2 - 9 \\ 8 + 6 & 4 - 3 \end{pmatrix} = \begin{pmatrix} -8 & -11 \\ 14 & 1 \end{pmatrix} \] 4. **Subtract \( C \)**: \[ (2A - 3B) - C = \begin{pmatrix} -8 & -11 \\ 14 & 1 \end{pmatrix} - \begin{pmatrix} -2 & -3 \\ -1 & 2 \end{pmatrix} = \begin{pmatrix} -8 + 2 & -11 + 3 \\ 14 + 1 & 1 - 2 \end{pmatrix} = \begin{pmatrix} -6 & -8 \\ 15 & -1 \end{pmatrix} \] ### (iv) Calculate \( A + (2B - C) \) 1. **Calculate \( 2B \)** (already calculated): \[ 2B = \begin{pmatrix} 8 & 6 \\ -4 & 2 \end{pmatrix} \] 2. **Subtract \( C \)**: \[ 2B - C = \begin{pmatrix} 8 & 6 \\ -4 & 2 \end{pmatrix} - \begin{pmatrix} -2 & -3 \\ -1 & 2 \end{pmatrix} = \begin{pmatrix} 8 + 2 & 6 + 3 \\ -4 + 1 & 2 - 2 \end{pmatrix} = \begin{pmatrix} 10 & 9 \\ -3 & 0 \end{pmatrix} \] 3. **Add \( A \)**: \[ A + (2B - C) = \begin{pmatrix} 2 & -1 \\ 4 & 2 \end{pmatrix} + \begin{pmatrix} 10 & 9 \\ -3 & 0 \end{pmatrix} = \begin{pmatrix} 2 + 10 & -1 + 9 \\ 4 - 3 & 2 + 0 \end{pmatrix} = \begin{pmatrix} 12 & 8 \\ 1 & 2 \end{pmatrix} \] ### (v) Calculate \( A + (B + C) \) 1. **Use \( B + C \)** (already calculated): \[ B + C = \begin{pmatrix} 2 & 0 \\ -3 & 3 \end{pmatrix} \] 2. **Add \( A \)**: \[ A + (B + C) = \begin{pmatrix} 2 & -1 \\ 4 & 2 \end{pmatrix} + \begin{pmatrix} 2 & 0 \\ -3 & 3 \end{pmatrix} = \begin{pmatrix} 2 + 2 & -1 + 0 \\ 4 - 3 & 2 + 3 \end{pmatrix} = \begin{pmatrix} 4 & -1 \\ 1 & 5 \end{pmatrix} \] ### (vi) Calculate \( (A + B) + C \) 1. **Calculate \( A + B \)**: \[ A + B = \begin{pmatrix} 2 & -1 \\ 4 & 2 \end{pmatrix} + \begin{pmatrix} 4 & 3 \\ -2 & 1 \end{pmatrix} = \begin{pmatrix} 2 + 4 & -1 + 3 \\ 4 - 2 & 2 + 1 \end{pmatrix} = \begin{pmatrix} 6 & 2 \\ 2 & 3 \end{pmatrix} \] 2. **Add \( C \)**: \[ (A + B) + C = \begin{pmatrix} 6 & 2 \\ 2 & 3 \end{pmatrix} + \begin{pmatrix} -2 & -3 \\ -1 & 2 \end{pmatrix} = \begin{pmatrix} 6 - 2 & 2 - 3 \\ 2 - 1 & 3 + 2 \end{pmatrix} = \begin{pmatrix} 4 & -1 \\ 1 & 5 \end{pmatrix} \] ### Summary of Results: 1. \( 2B + 3C = \begin{pmatrix} 2 & -3 \\ -7 & 8 \end{pmatrix} \) 2. \( -2A + (B + C) = \begin{pmatrix} -2 & 2 \\ -11 & -1 \end{pmatrix} \) 3. \( (2A - 3B) - C = \begin{pmatrix} -6 & -8 \\ 15 & -1 \end{pmatrix} \) 4. \( A + (2B - C) = \begin{pmatrix} 12 & 8 \\ 1 & 2 \end{pmatrix} \) 5. \( A + (B + C) = \begin{pmatrix} 4 & -1 \\ 1 & 5 \end{pmatrix} \) 6. \( (A + B) + C = \begin{pmatrix} 4 & -1 \\ 1 & 5 \end{pmatrix} \)
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