Chapter 7

Thinking Mathematically · 298 exercises

Problem 19

Graph each linear inequality. \(y>-4\)

3 step solution

Problem 19

Solve each system by the substitution method. Be sure to check all proposed solutions. \(\left\\{\begin{array}{l}2 x-y=-5 \\ x+5 y=14\end{array}\right.\)

5 step solution

Problem 19

Calculate the slope of the line passing through the given points. If the slope is undefined, so state. Then indicate whether the line rises, falls, is horizontal, or is vertical. \((5,1)\) and \((-2,1)\)

4 step solution

Problem 19

Plot the given point in a rectangular coordinate system. \((1.25,-3.25)\)

3 step solution

Problem 20

a. Create a scatter plot for the data in each table. b. Use the shape of the scatter plot to determine if the data are best modeled by a linear function, an exponential function, a logarithmic function, or a quadratic function. $$ \begin{array}{|c|r|} \hline \boldsymbol{x} & \boldsymbol{y} \\ \hline 0 & -4 \\ \hline 1 & -1 \\ \hline 2 & 0 \\ \hline 3 & -1 \\ \hline 4 & -4 \\ \hline \end{array} $$

4 step solution

Problem 20

What is an objective function in a linear programming problem?

2 step solution

Problem 20

Graph each linear inequality. \(y>-2\)

3 step solution

Problem 20

Solve each system by the substitution method. Be sure to check all proposed solutions. \(\left\\{\begin{array}{r}2 x+3 y=11 \\ x-4 y=0\end{array}\right.\)

6 step solution

Problem 20

Calculate the slope of the line passing through the given points. If the slope is undefined, so state. Then indicate whether the line rises, falls, is horizontal, or is vertical. \((-2,3)\) and \((1,3)\)

4 step solution

Problem 20

Plot the given point in a rectangular coordinate system. \((2.25,-4.25)\)

4 step solution

Problem 21

a. Create a scatter plot for the data in each table. b. Use the shape of the scatter plot to determine if the data are best modeled by a linear function, an exponential function, a logarithmic function, or a quadratic function. $$ \begin{array}{|c|c|} \hline \boldsymbol{x} & \boldsymbol{y} \\ \hline 0 & -3 \\ \hline 1 & -2 \\ \hline 2 & 0 \\ \hline 3 & 4 \\ \hline 4 & 12 \\ \hline \end{array} $$

3 step solution

Problem 21

What is a constraint in a linear programming problem? How is a constraint represented?

3 step solution

Problem 21

Graph each linear inequality. \(y \geq 0\)

3 step solution

Problem 21

Solve each system by the substitution method. Be sure to check all proposed solutions. \(\left\\{\begin{array}{l}2 x-y=3 \\ 5 x-2 y=10\end{array}\right.\)

4 step solution

Problem 21

Graph each equation in Exercises 21-32. Select integers for \(x\) from \(-3\) to 3 , inclusive. \(y=x^{2}-2\)

4 step solution

Problem 22

a. Create a scatter plot for the data in each table. b. Use the shape of the scatter plot to determine if the data are best modeled by a linear function, an exponential function, a logarithmic function, or a quadratic function. $$ \begin{array}{|c|r|} \hline \boldsymbol{x} & \boldsymbol{y} \\ \hline 0 & 4 \\ \hline 1 & 5 \\ \hline 2 & 7 \\ \hline 3 & 11 \\ \hline 4 & 19 \\ \hline \end{array} $$

3 step solution

Problem 22

In your own words, describe how to solve a linear programming problem.

5 step solution

Problem 22

Graph each linear inequality. \(x>0\)

3 step solution

Problem 22

Solve each system by the substitution method. Be sure to check all proposed solutions. \(\left\\{\begin{array}{r}-x+3 y=10 \\ 2 x+8 y=-6\end{array}\right.\)

5 step solution

Problem 22

Graph each equation in Exercises 21-32. Select integers for \(x\) from \(-3\) to 3 , inclusive. \(y=x^{2}+2\)

5 step solution

Problem 23

In Exercises 23-24, use a table of coordinates to graph each exponential function. Begin by selecting \(-2,-1,0,1\), and 2 for \(x\). Based on your graph, describe the shape of a scatter plot that can be modeled by \(f(x)=b^{x}, 0

3 step solution

Problem 23

Describe a situation in your life in which you would like to maximize something, but you are limited by at least two constraints. Can linear programming be used in this situation? Explain your answer.

4 step solution

Problem 23

In Exercises 23-38, graph the solution set of each system of inequalities. \(\left\\{\begin{array}{l}3 x+6 y \leq 6 \\ 2 x+y \leq 8\end{array}\right.\)

3 step solution

Problem 23

Solve each system by the substitution method. Be sure to check all proposed solutions. \(\left\\{\begin{array}{rr}x+8 y= & 6 \\ 2 x+4 y= & -3\end{array}\right.\)

4 step solution

Problem 23

Graph each equation in Exercises 21-32. Select integers for \(x\) from \(-3\) to 3 , inclusive. \(y=x-2\)

3 step solution

Problem 24

Use a table of coordinates to graph each exponential function. Begin by selecting \(-2,-1,0,1\), and 2 for \(x\). Based on your graph, describe the shape of a scatter plot that can be modeled by \(f(x)=b^{x}, 0

4 step solution

Problem 24

Graph the solution set of each system of inequalities. \(\left\\{\begin{array}{l}x-y \geq 4 \\ x+y \leq 6\end{array}\right.\)

3 step solution

Problem 24

Solve each system by the substitution method. Be sure to check all proposed solutions. \(\left\\{\begin{aligned}-4 x+y &=-11 \\ 2 x-3 y &=5 \end{aligned}\right.\)

6 step solution

Problem 24

Graph each equation in Exercises 21-32. Select integers for \(x\) from \(-3\) to 3 , inclusive. \(y=x+2\)

3 step solution

Problem 25

Graph the solution set of each system of inequalities. \(\left\\{\begin{array}{r}2 x+y<3 \\ x-y>2\end{array}\right.\)

5 step solution

Problem 25

In Exercises 25-36, solve each system by the addition method. Be sure to check all proposed solutions. \(\left\\{\begin{array}{l}x+y=1 \\ x-y=3\end{array}\right.\)

5 step solution

Problem 25

Graph each equation in Exercises 21-32. Select integers for \(x\) from \(-3\) to 3 , inclusive. \(y=2 x+1\)

4 step solution

Problem 26

Use the directions for Exercises 7-8 to graph each logarithmic function. Based on your graph, describe the shape of a scatter plot that can be modeled by \(f(x)=\log _{b} x, 0

3 step solution

Problem 26

Graph the solution set of each system of inequalities. \(\left\\{\begin{array}{c}x+y<4 \\ 4 x-2 y<6\end{array}\right.\)

3 step solution

Problem 26

Solve each system by the addition method. Be sure to check all proposed solutions. \(\left\\{\begin{array}{l}x+y=6 \\ x-y=-2\end{array}\right.\)

4 step solution

Problem 26

Graph each equation in Exercises 21-32. Select integers for \(x\) from \(-3\) to 3 , inclusive. \(y=2 x-4\)

3 step solution

Problem 27

In Exercises 27-28, use the directions for Exercises 9-14 to graph each quadratic function. Use the quadratic formula to find \(x\)-intercepts, rounded to the nearest tenth. \(f(x)=-2 x^{2}+4 x+5\)

4 step solution

Problem 27

Graph the solution set of each system of inequalities. \(\left\\{\begin{array}{r}2 x+y<4 \\ x-y>4\end{array}\right.\)

3 step solution

Problem 27

Solve each system by the addition method. Be sure to check all proposed solutions. \(\left\\{\begin{array}{l}2 x+3 y=6 \\ 2 x-3 y=6\end{array}\right.\)

5 step solution

Problem 27

Graph each equation in Exercises 21-32. Select integers for \(x\) from \(-3\) to 3 , inclusive. \(y=-\frac{1}{2} x\)

3 step solution

Problem 28

Use the directions for Exercises 9-14 to graph each quadratic function. Use the quadratic formula to find \(x\)-intercepts, rounded to the nearest tenth. \(f(x)=-3 x^{2}+6 x-2\)

3 step solution

Problem 28

Graph the solution set of each system of inequalities. \(\left\\{\begin{array}{r}2 x-y<3 \\ x+y<6\end{array}\right.\)

3 step solution

Problem 28

Solve each system by the addition method. Be sure to check all proposed solutions. \(\left\\{\begin{array}{l}3 x+2 y=14 \\ 3 x-2 y=10\end{array}\right.\)

6 step solution

Problem 28

Graph each equation in Exercises 21-32. Select integers for \(x\) from \(-3\) to 3 , inclusive. \(y=-\frac{1}{2} x+2\)

4 step solution

Problem 29

In Exercises 29-30, find the vertex for the parabola whose equation is given by writing the equation in the form \(y=a x^{2}+b x+c\).\ \(y=(x-3)^{2}+2\)

2 step solution

Problem 29

Group members should choose a particular field of interest. Research how linear programming is used to solve problems in that field. If possible, investigate the solution of a specific practical problem. Present a report on your findings, including the contributions of George Dantzig, Narendra Karmarkar, and L. G. Khachion to linear programming.

5 step solution

Problem 29

Graph the solution set of each system of inequalities. \(\left\\{\begin{array}{l}x \geq 2 \\ y \leq 3\end{array}\right.\)

4 step solution

Problem 29

Solve each system by the addition method. Be sure to check all proposed solutions. \(\left\\{\begin{array}{r}x+2 y=2 \\ -4 x+3 y=25\end{array}\right.\)

5 step solution

Problem 29

Graph each equation in Exercises 21-32. Select integers for \(x\) from \(-3\) to 3 , inclusive. \(y=x^{3}\)

3 step solution

Problem 30

In Exercises 29-30, find the vertex for the parabola whose equation is given by writing the equation in the form \(y=a x^{2}+b x+c\).\ \(y=(x-4)^{2}+3\)

2 step solution

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