The current and estimated resident populations (in percent) of blacks and Hispanics in the United States for the years $1990-2050$ are modeled by the linear functions defined below.

$$\begin{array}{ll} y=.0515 x+12.3 & \text { Blacks } \\ y=.255 x+9.01 & \text { Hispanics } \end{array}$$

In the case, $x$ represents the number of years since 1990.

(a) Solve the system to find the year when these population percents will be equal.

Give all solutions of the nonlinear system of equations, including those with nonreal complex components.

$$\begin{array}{r} x^2+y^2=10 \\ 2 x^2-y^2=17 \end{array}$$

Graph the inequality.

When graphing $y \leq 3 x-6$, would you shade above or below the line $y=3 x-6$ ? Explain your answer.

Find the value of the determinant.

$$\left|\begin{array}{rrr}2 & 1 & -1 \\ 4 & 7 & -2 \\ 2 & 4 & 0\end{array}\right|$$

This exercise has introduced methods for solving systems of equations, including substitution and elimination, and matrix methods such as the Gauss-Jordan method and Cramer's rule. Use each method at least once when solving the systems. Include solutions with nonreal complex number components. For systems with infinitely many solutions, write the solution set using an arbitrary variable.

$$\begin{array}{r} x+5 y+3 z=9 \\ 2 x+9 y+7 z=5 \end{array}$$

Solve the given system by substitution.

$$\begin{aligned} &4 y=2 x-4 \\ &x-y=4 \end{aligned}$$

Find the inverse, if it exists, for the matrix.

$$\left[\begin{array}{rrr}1 & 0 & 0 \\ 0 & -1 & 0 \\ 1 & 0 & 1\end{array}\right]$$

Find two numbers such that their sum is $-1$ and the sum of their squares is $61$ .

Give all solutions of the nonlinear system of equations, including those with nonreal complex components.

$$\begin{aligned} & x^2+y^2=8 \\ & x^2-y^2=0 \end{aligned}$$

Use the Gauss-Jordan method to solve the system of equations. For systems in three variables with infinitely many solutions, give the solution with $z$ arbitrary; for any such equations with four variables, let $w$ be the arbitrary variable.

$$\begin{aligned} &3 x+2 y=-9 \\ &2 x-5 y=-6 \end{aligned}$$

Find the size of the matrix. Identify any square, col

$$\left[\begin{array}{l}2 \\ 4\end{array}\right]$$

This exercise has introduced methods for solving systems of equations, including substitution and elimination, and matrix methods such as the Gauss-Jordan method and Cramer's rule. Use each method at least once when solving the systems. Include solutions with nonreal complex number components. For systems with infinitely many solutions, write the solution set using an arbitrary variable.

$$\begin{aligned} & -5 x+2 y+z=5 \\ & -3 x-2 y-z=3 \\ & -x+6 y=1 \end{aligned}$$

Write a system of linear equations, and then use the system to solve the problem.

The Waputi Indians make woven blankets, rugs, and skirts. Each blanket requires $24 \mathrm{hr}$ for spinning the yarn, $4 \mathrm{hr}$ for dyeing the yarn, and $15 \mathrm{hr}$ for weaving. Rugs require $30$,$5$ , and $18 \mathrm{hr}$ and skirts $12$,$3$ , and $9 \mathrm{hr}$, respectively. If there are $306$,$59$ , and $201 \mathrm{hr}$ available for spinning, dyeing, and weaving, respectively, how many of each item can be made?

(Hint: Simplify the equations you write, if possible, before solving the system.)

Find the value of the determinant.

$$\left|\begin{array}{rrr}1 & 2 & 0 \\ -1 & 2 & -1 \\ 0 & 1 & 4\end{array}\right|$$