91Ó°ÊÓ

Fill in the blanks. A determinant is number that is associated with a __ matrix.

Fill in the blanks. In the equation \(x+3 y=-1,\) the \(x\) -term has an understood _____________ of 1

Fill in the blanks. When we add the two equations of the system \(\left\\{\begin{array}{l}x+y=5 \\\ x-y=-3\end{array}\right.\) the \(y\) -terms are _____________.

Given the equation \(3 x+y=-4\) a. solve for \(x\) b. solve for \(y\) c. Which variable was easier to solve for? Explain why.

NOTATION Write each percent as a decimal. a. \(6 \%\) b. \(4.8 \%\) c. \(13 \frac{1}{2} \%\)

Determine whether the ordered pair is a solution of the system of equations. See Example 1. $$ (-1,2) ;\left\\{\begin{array}{l} 3 x-y=-5 \\ x-y=-4 \end{array}\right. $$

Evaluate each determinant. $$ \left|\begin{array}{ll} 2 & 3 \\ 2 & 5 \end{array}\right| $$

Perform each of the following elementary row operations on the augumented matrix \(\left[\begin{array}{rrr}-3 & 1 & -6 \\ 1 & -4 & 4\end{array}\right].\) $$ -\frac{1}{3} R_{1} $$

Determine whether the ordered pair is a solution of the system of equations. See Example 1. $$ (-0.2,0.5) ;\left\\{\begin{array}{l} 2 x+5 y=2.1 \\ 5 x+y=-0.5 \end{array}\right. $$

Solve each system by elimination. See Examples 3 and 4 $$ \left\\{\begin{array}{l} x-y=7 \\ x+y=11 \end{array}\right. $$