St. Britto Hr. Sec. School - Madurai
11th Maths Weekly Test -1( Matrices and Determinants )-Aug 2020
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Consider the matrix Aa=\(\begin{bmatrix} cos \alpha & -sin\alpha \\ sin\alpha & cos\alpha \end{bmatrix}\)
Find all possible real values of α satisfying the condition \(A\alpha +A^T_{\alpha}=I\) -
Prove that \(\left[ \begin{matrix} 1 & a & { a }^{ 2 } \\ 1 & b & { b }^{ 2 } \\ 1 & c & { c }^{ 2 } \end{matrix} \right] =\left( a-b \right) \left( b-c \right) \left( c-a \right) \)
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Compute |A| using Sarrus rule if A=\(\begin{bmatrix} 3& 4 & 1 \\ 0 &-1 &2 \\ 5 & -2 & 6 \end{bmatrix}\) .
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Construct a 2 × 3 matrix whose (i, j)th element is given by \(a_ij={\sqrt{3}\over 2}|2i-3j|(1\le i\le2,1\le j\le3)\) .
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Determine the values of a so that the following matrices are singular: A=\(\begin{bmatrix} 7& 3 \\ -2 & a \end{bmatrix}\)
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Show that f(x)f(y)=f(x+y) where f(x)=\(\begin{bmatrix} cos \ x & -sin \ x & 0 \\ sin x & cos x & 0 \\ 0 & 0 & 1 \end{bmatrix}\).
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Prove that \(\left| \begin{matrix} a+b+c & -c & -b \\ -c & a+b+c & -a \\ -b & -a & a+b+c \end{matrix} \right| =2\left( a+b \right) \left( b+c \right) \left( c+a \right) \)
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Using factor method show that \(\left| \begin{matrix} 1 & a & { a }^{ 2 } \\ 1 & b & { b }^{ 2 } \\ 1 & c & { c }^{ 2 } \end{matrix} \right| \) = (a - b) (b - c) (c - a).
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If \(A=\left[ \begin{matrix} 1 & 8 \\ 4 & 3 \end{matrix} \right] \quad B=\left[ \begin{matrix} 1 & 3 \\ 7 & 4 \end{matrix} \right] \quad C=\left[ \begin{matrix} -4 & 6 \\ 3 & -5 \end{matrix} \right] \)
Prove that
(l) AB ≠ BA
(it)A(BC) = (AB)C
(iii) A(B + C) = AB + AC
(iv) AI = IA = A -
Without expanding, evaluate the following determinants:
\(\begin{vmatrix} 2& 3 &4 \\ 5 & 6 & 8 \\ 6x & 9x &12x \end{vmatrix}\) -
If \(\begin{bmatrix} 0 & p& 3 \\ 2 & q^2 & -1 \\ r & 1 & 0 \end{bmatrix}\) is skew-symmetric, find the values of p,q, and r.
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If A and B are symmetric matrices of same order, prove that
AB + BA is a symmetric matrix