1-Review
Take this test as you would take a test in class. When you are finished, check your work against the answers.
Graph the system and estimate the solution.
- \(\left\{ \begin{align} y&=\frac{2}{3}x+1 \\ y&=-\frac{1}{2}x-\frac{5}{2} \end{align}\right.\)
- \(\left\{ \begin{alignat}{3} 2x&+&y&=&3 \\ x&-&y&=&0 \end{alignat} \right.\)
Graph the system of inequalities.
- \(\left\{ \begin{align} y& < 2x+1 \\ y& ≥ -x-2 \end{align} \right.\)
Solve the system algebraically.
- \(\left\{ \begin{align} y=x+2 \\ 2x-2y=3 \end{align} \right.\)
- \(\left\{ \begin{alignat}{3} 3x&-&2y&=&-7 \\ x&+&2y&=&11 \end{alignat} \right.\)
- Jim has two jobs. The first week he works 2 hours at job A and 3 hours at job B and earns $57.50. The second week he works 5 hours at job A and 2 hours at job B and earns $75. What is his pay rate at job A?
- How do you know if there are many solutions when you are solving algebraically?
Is the given point a solution to the system?
- \(\left\{ \begin{alignat}{4} x&-&y&+&2z&=&-7 \\ &&y&-&3z&=&11 \\ x&&&+&z&=&-2 \end{alignat}\right.\) point (1, 2, −3)
Solve the system algebraically.
- \(\left\{ \begin{alignat}{4} x&+&y&+&z&=&4 \\ -x&+&y&-&2z&=&-4 \\ &-&2y&-&z&=&-4 \end{alignat}\right.\)
- What does the graph of a linear equation in three variables look like?
Simplify.
- \(\left[\begin{matrix}1&8\\-3&5\\\end{matrix}\right]-\left[\begin{matrix}-2&0\\-9&-4\\\end{matrix}\right]\)
- \(3\left[\begin{matrix}2&8\\\end{matrix}\right]\)
- \(2\left[\begin{matrix}3\\-4\\\end{matrix}\right]+\left[\begin{matrix}1\\5\\\end{matrix}\right]\)
Simplify.
- \(\left[\begin{matrix}1&2\\\end{matrix}\right]\left[\begin{matrix}-2&3\\-1&4\\\end{matrix}\right]\)
- \(\left[\begin{matrix}1&2\\-2&-1\\\end{matrix}\right]\left[\begin{matrix}3&-3\\1&-1\\\end{matrix}\right]\)
- How do you know if two matrices can be multiplied?
Evaluate the determinant.
- \(\left|\begin{matrix}3&-1\\2&7\\\end{matrix}\right|\)
- \(\left|\begin{matrix}1&3&0\\-2&-1&2\\4&0&-1\\\end{matrix}\right|\)
- Find the area of the triangle with vertices (1, 2), (0, −2), (3, 1).
- What is the product of a matrix with its inverse?
- Find inverse of \(\left[\begin{matrix}2&1\\1&-3\\\end{matrix}\right]\).
- Use an inverse to solve \(\left\{ \begin{alignat}{3} 2x&+&y&=&8 \\ x&-&3y&=&-3 \end{alignat} \right.\).
Answers
- (−3, −1)
- (1, 1)
- No solution
- (1, 5)
- $10 per hour
- All variables are eliminated and the result is a true statement.
- Yes
- (1, 1, 2)
- A plane
- \(\left[\begin{matrix}3&8\\6&9\\\end{matrix}\right]\)
- \(\left[\begin{matrix}6&24\\\end{matrix}\right]\)
- \(\left[\begin{matrix}7\\-3\\\end{matrix}\right]\)
- [−4 11]
- \(\left[\begin{matrix}5&-5\\-7&7\\\end{matrix}\right]\)
- The number of columns in the 1st matrix = number of rows in the 2nd matrix
- 23
- 19
- \(\frac{9}{2}\)
- Identity matrix
- \(\left[\begin{matrix}\frac{3}{7}&\frac{1}{7}\\\frac{1}{7}&-\frac{2}{7}\\\end{matrix}\right]\)
- (3, 2)