Matrices and determinants

2000017108

Level: 
B
For what values of the real parameters \(a\) and \(b\) will the matrices given below be inverse to each other? \[ \left (\array{ a& 7 \cr 3 & 1 \cr} \right ), ~ \left (\array{ -\frac1{16}& \frac7{16} \cr b & -\frac5{16} \cr} \right ) \]
\(a=5\), \(b=\frac3{16}\)
\(a=-5\), \(b=\frac3{16}\)
\(a=5\), \(b=-\frac3{16}\)
\(a=-5\), \(b=-\frac3{16}\)

2000017107

Level: 
B
Compute the inverse matrix to the matrix: \[ \left (\array{ \frac17& -\frac3{14}\cr \frac27 & \frac1{14}} \right ) \]
\[ \left (\array{ 1& 3\cr -4& 2}\right ) \]
\[ \left (\array{ 1& 3\cr 4& -2}\right ) \]
\[ \left (\array{ 1& 3\cr 2& -4}\right ) \]
\[ \left (\array{ 2& -3\cr 4& 1}\right ) \]

2000017106

Level: 
B
For what values of the real parameters \(a\), \(b\), \(c\), \(d\), \(e\) and \(f\) will the matrices given below be inverse to each other? \[ \left (\array{ 1& 0 & 0\cr 0 & 1 & 1 \cr a& b & c} \right ), \left (\array{ d& e & f\cr -1 & 1 & -1 \cr 1& 0 & 1} \right ) \]
\(a=-1\), \(b=0\), \(c=1\), \(d=1\), \(e=0\), \(f=0\)
\(a=1\), \(b=0\), \(c=1\), \(d=-1\), \(e=0\), \(f=1\)
\(a=-1\), \(b=0\), \(c=-1\), \(d=1\), \(e=0\), \(f=0\)
\(a=1\), \(b=0\), \(c=-1\), \(d=-1\), \(e=1\), \(f=0\)

2000017105

Level: 
B
Let \(x\) be a real number. Determine the inverse matrix to the matrix: \[ \left (\array{ \cos x& -\sin x \cr \sin x & \cos x \cr} \right ) \]
\[ \left (\array{ \cos x& \sin x \cr -\sin x & \cos x \cr} \right ) \]
\[ \left (\array{ 1& 0 \cr 0 & 1 \cr} \right ) \]
\[ \left (\array{ \frac{\cos x}{\sin 2x}& \frac{\sin x}{\sin 2x}\cr -\frac{\sin x}{\sin 2x}& \frac{\cos x}{\sin 2x} \cr} \right ) \]
The inverse matrix does not exist.

2000017103

Level: 
B
Compute the inverse matrix to the matrix: \[ \left (\array{ 1& 0 & 0\cr 0 & 1 & 1 \cr -1& 0 & 1} \right ) \]
\[ \left (\array{ 1& 0 & 0\cr -1 & 1 & -1 \cr 1& 0 & 1 } \right ) \]
\[ \left (\array{ 1& 0 & 0\cr 1 & 1 & 1 \cr 1& 0 & 1 } \right ) \]
\[ \left (\array{ 1& 0 & 0\cr 1 & 1 & 1 \cr -1& 0 & -1 } \right ) \]
\[ \left (\array{ -1& 0 & 0\cr -1 & 1 & -1 \cr 1& 0 & -1 } \right ) \]

2000017102

Level: 
B
Compute the inverse matrix to the matrix: \[ \left (\array{ 4& 3 & 0\cr 2 & 1 & 2 \cr 0& 0 & -1 } \right ) \]
\[ \left (\array{ -\frac12& \frac32 & 3\cr 1 & -2 & -4 \cr 0& 0 & -1 } \right ) \]
\[ \left (\array{ \frac12& \frac32 & 3\cr 1 & -2 & -4 \cr 0& 0 & 1 } \right ) \]
\[ \left (\array{ -\frac12& \frac32 & -3\cr -1 & -2 & -4 \cr 0& 0 & -1 } \right ) \]
\[ \left (\array{ -\frac12& \frac32 & 3\cr 1 & 2 & -4 \cr 0& 0 & -1 } \right ) \]

2010006701

Level: 
A
Identify a true statement related to the following matrix \(A\). \[ A = \left (\array{ 2& 4 & -3& 7\cr 9 & -5 & -1 & 8 \cr 11& 0 & 8& 12 \cr -7 & -8 & 1& 13 \cr 9& 10 & -6& 2 } \right ) \]
\(A\) is a \(5\times 4\) matrix and \(a_{(2,\, 3)} = -1\).
\(A\) is a \(5\times 4\) matrix and \(a_{(2,\, 3)} = 0\).
\(A\) is a \(4\times 5\) matrix and \(a_{(2,\, 3)} = 0\).
\(A\) is a \(4\times 5\) matrix and \(a_{(2,\, 3)} = -1\).