Determinants and their Properties
Matrix and Determinant

79020 If \(\mathbf{a}^{2}+b^{2}+c^{2}=-2\)
and \(f(x)=\left|\begin{array}{ccc}1+a^{2} x & \left(1+b^{2}\right) x & \left(1+c^{2}\right) x \\ \left(1+a^{2}\right) x & 1+b^{2} x & \left(1+c^{2}\right) x \\ \left(1+a^{2}\right) x & \left(1+b^{2}\right) x & 1+c^{2} x\end{array}\right|\)
then \(f(x)\) is a polynomial of degree

1 3
2 2
3 1
4 0
Matrix and Determinant

79021 Matrix \(M_{r}\) is defined as \(M_{r}=\left[\begin{array}{cc}r & r-1 \\ r-1 & r\end{array}\right]\) \(r \in N\) Value of \(\operatorname{det}\left(M_{1}\right)+\operatorname{det}\left(M_{2}\right)+\operatorname{det}\left(M_{3}\right)+\) ... + det \(\left(\mathbf{M}_{2007}\right)\) is

1 2007
2 2008
3 \((2008)^{2}\)
4 \((2007)^{2}\)
Matrix and Determinant

79022 If \(y y^{2} 1+y^{3}=0\) then
\(\left|\begin{array}{lll}z & z^{2} & 1+z^{3}\end{array}\right|\)

1 \(z=x y\)
2 \(z=\frac{1}{x y}\)
3 \(z=-\frac{1}{x y}\)
4 None of these
Matrix and Determinant

79023 If \(\cos 2 \theta=0\), then
\(\left|\begin{array}{ccc}0 & \cos \theta & \sin \theta \\ \cos \theta & \sin \theta & 0 \\ \sin \theta & 0 & \cos \theta\end{array}\right|^{2}=\)

1 1
2 4
3 \(1 / 4\)
4 \(1 / 2\)
Matrix and Determinant

79020 If \(\mathbf{a}^{2}+b^{2}+c^{2}=-2\)
and \(f(x)=\left|\begin{array}{ccc}1+a^{2} x & \left(1+b^{2}\right) x & \left(1+c^{2}\right) x \\ \left(1+a^{2}\right) x & 1+b^{2} x & \left(1+c^{2}\right) x \\ \left(1+a^{2}\right) x & \left(1+b^{2}\right) x & 1+c^{2} x\end{array}\right|\)
then \(f(x)\) is a polynomial of degree

1 3
2 2
3 1
4 0
Matrix and Determinant

79021 Matrix \(M_{r}\) is defined as \(M_{r}=\left[\begin{array}{cc}r & r-1 \\ r-1 & r\end{array}\right]\) \(r \in N\) Value of \(\operatorname{det}\left(M_{1}\right)+\operatorname{det}\left(M_{2}\right)+\operatorname{det}\left(M_{3}\right)+\) ... + det \(\left(\mathbf{M}_{2007}\right)\) is

1 2007
2 2008
3 \((2008)^{2}\)
4 \((2007)^{2}\)
Matrix and Determinant

79022 If \(y y^{2} 1+y^{3}=0\) then
\(\left|\begin{array}{lll}z & z^{2} & 1+z^{3}\end{array}\right|\)

1 \(z=x y\)
2 \(z=\frac{1}{x y}\)
3 \(z=-\frac{1}{x y}\)
4 None of these
Matrix and Determinant

79023 If \(\cos 2 \theta=0\), then
\(\left|\begin{array}{ccc}0 & \cos \theta & \sin \theta \\ \cos \theta & \sin \theta & 0 \\ \sin \theta & 0 & \cos \theta\end{array}\right|^{2}=\)

1 1
2 4
3 \(1 / 4\)
4 \(1 / 2\)
Matrix and Determinant

79020 If \(\mathbf{a}^{2}+b^{2}+c^{2}=-2\)
and \(f(x)=\left|\begin{array}{ccc}1+a^{2} x & \left(1+b^{2}\right) x & \left(1+c^{2}\right) x \\ \left(1+a^{2}\right) x & 1+b^{2} x & \left(1+c^{2}\right) x \\ \left(1+a^{2}\right) x & \left(1+b^{2}\right) x & 1+c^{2} x\end{array}\right|\)
then \(f(x)\) is a polynomial of degree

1 3
2 2
3 1
4 0
Matrix and Determinant

79021 Matrix \(M_{r}\) is defined as \(M_{r}=\left[\begin{array}{cc}r & r-1 \\ r-1 & r\end{array}\right]\) \(r \in N\) Value of \(\operatorname{det}\left(M_{1}\right)+\operatorname{det}\left(M_{2}\right)+\operatorname{det}\left(M_{3}\right)+\) ... + det \(\left(\mathbf{M}_{2007}\right)\) is

1 2007
2 2008
3 \((2008)^{2}\)
4 \((2007)^{2}\)
Matrix and Determinant

79022 If \(y y^{2} 1+y^{3}=0\) then
\(\left|\begin{array}{lll}z & z^{2} & 1+z^{3}\end{array}\right|\)

1 \(z=x y\)
2 \(z=\frac{1}{x y}\)
3 \(z=-\frac{1}{x y}\)
4 None of these
Matrix and Determinant

79023 If \(\cos 2 \theta=0\), then
\(\left|\begin{array}{ccc}0 & \cos \theta & \sin \theta \\ \cos \theta & \sin \theta & 0 \\ \sin \theta & 0 & \cos \theta\end{array}\right|^{2}=\)

1 1
2 4
3 \(1 / 4\)
4 \(1 / 2\)
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Matrix and Determinant

79020 If \(\mathbf{a}^{2}+b^{2}+c^{2}=-2\)
and \(f(x)=\left|\begin{array}{ccc}1+a^{2} x & \left(1+b^{2}\right) x & \left(1+c^{2}\right) x \\ \left(1+a^{2}\right) x & 1+b^{2} x & \left(1+c^{2}\right) x \\ \left(1+a^{2}\right) x & \left(1+b^{2}\right) x & 1+c^{2} x\end{array}\right|\)
then \(f(x)\) is a polynomial of degree

1 3
2 2
3 1
4 0
Matrix and Determinant

79021 Matrix \(M_{r}\) is defined as \(M_{r}=\left[\begin{array}{cc}r & r-1 \\ r-1 & r\end{array}\right]\) \(r \in N\) Value of \(\operatorname{det}\left(M_{1}\right)+\operatorname{det}\left(M_{2}\right)+\operatorname{det}\left(M_{3}\right)+\) ... + det \(\left(\mathbf{M}_{2007}\right)\) is

1 2007
2 2008
3 \((2008)^{2}\)
4 \((2007)^{2}\)
Matrix and Determinant

79022 If \(y y^{2} 1+y^{3}=0\) then
\(\left|\begin{array}{lll}z & z^{2} & 1+z^{3}\end{array}\right|\)

1 \(z=x y\)
2 \(z=\frac{1}{x y}\)
3 \(z=-\frac{1}{x y}\)
4 None of these
Matrix and Determinant

79023 If \(\cos 2 \theta=0\), then
\(\left|\begin{array}{ccc}0 & \cos \theta & \sin \theta \\ \cos \theta & \sin \theta & 0 \\ \sin \theta & 0 & \cos \theta\end{array}\right|^{2}=\)

1 1
2 4
3 \(1 / 4\)
4 \(1 / 2\)