Systems of linear equations and inequalities

9000019909

Level: 
B
The augmented matrix of a system of three equations with three unknowns is the following matrix \(M'\). Identify the matrix which is row equivalent to \(M'\). \[ M' = \left(\begin{array}{ccc|c} 1 & 2 & 4 & 14\\ -1 & 0 & 3 & 7\\ 3 & 1 & -2 & 42 \end{array}\right) \]
\(\left(\begin{array}{ccc|c} 1 & 2 & 4 & 14\\ 0 & 2 & 7 & 21\\ 0 & 0 & 7 & 105 \end{array}\right)\)
\(\left(\begin{array}{ccc|c} 1 & 2 & 4 & 14\\ 0 & 2 & 7 & 21\\ 0 & 0 & -8 & 70 \end{array}\right)\)
\(\left(\begin{array}{ccc|c} 1 & 2 & 4 & 14\\ 0 & 2 & 7 & 21\\ 0 & 0 & -29 & -147 \end{array}\right)\)
\(\left(\begin{array}{ccc|c} 1 & 2 & 4 & 14\\ 0 & 2 & 1 & 7\\ 0 & 0 & -23 & 35 \end{array}\right)\)

9000019910

Level: 
B
The augmented matrix of a system of three equations with three unknowns is row equivalent to the following matrix \(A'\). Find the solution of the system. \[ A' = \left(\begin{array}{ccc|c} -1 & -6 & 1 &-20\\ 0 & 5 & 4 & -12\\ 0 & 0 & 0 & -8 \end{array}\right) \]
no solution
\(\left [-\frac{172} {5} ;-\frac{12} {5} ;0\right ]\)
\([-12t;4t;-8t],\ t\in \mathbb{R}\)
\(\left [-12;4;-8\right ]\)

9000007206

Level: 
A
Consider the linear system: \[ \begin{aligned}2x - 3y - 12& = 0,& \\\text{???}\quad & = 0. \\ \end{aligned} \] In the following list, identify the missing second equation if you know that the system does not have a solution.
\(- 6x + 9y - 9 = 0\)
\(2x + 3y - 6 = 0\)
\(- 4x + 6y + 24 = 0\)
\(x + 2y - 12 = 0\)