Systems of linear equations and inequalities

9000019907

Level: 
B
The augmented matrix of a system of three equations with three unknowns is row equivalent with the following matrix \(A'\). Find the solution of the system. \[ A' = \left(\begin{array}{ccc|c} 1 & 2 & 4 & 0\\ 0 & 2 & 7 & 7\\ 0 & 0 & 7 & 35 \end{array}\right) \]
\([8;-14;5]\)
\([-62;21;5]\)
\([8;14;-5]\)
\([-22;-21;5]\)

9000019908

Level: 
B
The augmented matrix of a system of three equations with three unknowns is row equivalent with the following matrix \(A'\). Find the solution of the system. \[ A' = \left(\begin{array}{ccc|c} -1 & 0 & 1 &-1\\ 0 & 7 & 2 & -1\\ 0 & 0 & 30 & 6 \end{array}\right) \]
\(\left [\frac{6} {5};-\frac{1} {5}; \frac{1} {5}\right ]_{}\)
\(\left [\frac{1} {5};-\frac{1} {5}; \frac{6} {5}\right ]\)
\(\left [\frac{1} {5};-\frac{6} {5};-\frac{1} {5}\right ]\)
\(\left [-\frac{6} {5}; \frac{1} {5}; \frac{1} {5}\right ]\)

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
\(\left [-\frac{172} {5} ;-\frac{12} {5} ;0\right ]\)
\([-12t;4t;-8t],\ t\in \mathbb{R}\)
\(\left [-12;4;-8\right ]\)

9000022904

Level: 
B
Find the values of a real parameter \(t\) which ensure that the following system has a unique solution. \[ \begin{alignedat}{80} 2x & + &y & + &t & = - &2 & & & & & & & & \\ - 4x & - 2 &y & + &1 & = &0 & & & & & & & & \\\end{alignedat}\]
\(t\in \emptyset \)
\(t\in \mathbb{R}\)
\(t = 3\)
\(t = 1\)
\(t\in \mathbb{R}\setminus \{3\}\)

9000022905

Level: 
B
Find the values of a real parameter \(t\) which ensure that the following system has a unique solution. \[ \begin{alignedat}{80} tx & + &y & + &3 & = 0 & & & & & & \\4x & - 2 &y & + &1 & = 0 & & & & & & \\\end{alignedat}\]
\(t\in \mathbb{R}\setminus \{ - 2\}\)
\(t\in \mathbb{R}\)
\(t = -2\)
\(t\in \emptyset \)

9000022906

Level: 
B
Find the values of a real parameter \(t\) which ensure that the following system has a unique solution \([a,b]\) such that both \(a\) and \(b\) are positive real numbers. \[ \begin{alignedat}{80} a & - &tb & = - &2 & & & & & & \\a & + 2 &tb & = &0 & & & & & & \\\end{alignedat}\]
\(t\in \emptyset \)
\(t\in \mathbb{R}^{+}\)
\(t\in \mathbb{R}^{-}\)
\(t = 0\)
\(t\in \mathbb{R}\)