Let \( f(z) = \dfrac{1}{z^2 + 6z + 9} \) defined in the complex plane. The integral \( \oint_{c} f(z) \, dz \) over the contour of a circle \( c \) with center at the origin and unit radius is \(\underline{\hspace{2cm}}\).
The determinant of the matrix \( M \) shown below is \(\underline{\hspace{2cm}}\). \[ M = \begin{bmatrix} 1 & 2 & 0 & 0 \\ 3 & 4 & 0 & 0 \\ 0 & 0 & 4 & 3 \\ 0 & 0 & 0 & 1 \end{bmatrix} \]
Given \( A = \begin{pmatrix} 2 & 5 \\ 0 & 3 \end{pmatrix} \), the value of the determinant \( |A^4 - 5A^3 + 6A^2 + 2I| \) is \(\underline{\hspace{2cm}}\).
\[ \lim_{x \to 0} \frac{x^2}{\sin x} \]
The 2×2 matrices P and Q satisfy the following relations: The matrix Q is equal to _______.
The table below shows the carbon content of four samples of powdered coal. If these four samples are mixed completely, what would be the resultant carbon percentage of the mixture by weight?
A real \( 2 \times 2 \) non-singular matrix \( A \) with repeated eigenvalue is given as where \( x \) is a real positive number. The value of \( x \) (rounded off to one decimal place) is _________.