16 Solve the system of equations using matrices. Use the Gaussian elimination method with back-substitution. \[ \begin{array}{r}x+y-z=-4 \\ 4 x-y+z=-1 \\ -x+5 y-4 z=1\end{array} \] The solution set is \( \{(\square, \square, \square)\} \). (Simplify your answers.)

Factor completely: \[ 2 u^{4} w^{4}-2 w^{4} \]

Factor completely: \[ 32 v^{3}-2 v^{3} x^{4} \]

(a4) The solution set of the equation : \( \sqrt[3]{x^{2}}-3 \sqrt[3]{x}+2=0 \) is \( \{1,8\} \) \( \begin{array}{llll}\text { (a) }\{1, & \text { (b) }\{9,3\} & \text { (c) }\{8\} & \text { (d) }\{1\}\end{array} \)

Determine the geometric sequence if the second term is \( \frac{1}{9} \) and the sixth term is \( \frac{1}{729} \)

4. Diketahui \( f(x)=a \), maka \( f(2)=\ldots \) A. \( 2 f(x) \) B. \( 2 a \) C. 2 D. \( f(x) \) E. \( a \)