Chapter 4

Read Exercise \(72 .\) Then use a graphing utility to solve the systems. $$\left\\{\begin{array}{l}x+2 y=4 \\ x-y=4\end{array}\right.$$

Read Exercise \(72 .\) Then use a graphing utility to solve the systems. $$\left\\{\begin{array}{l}2 x-3 y=10 \\ 4 x+3 y=20\end{array}\right.$$

Read Exercise \(72 .\) Then use a graphing utility to solve the systems. $$\left\\{\begin{array}{c}3 x-y=5 \\ -5 x+2 y=-10\end{array}\right.$$

Read Exercise \(72 .\) Then use a graphing utility to solve the systems. $$\left\\{\begin{array}{l}2 x-3 y=7 \\ 3 x+5 y=1\end{array}\right.$$

Read Exercise \(72 .\) Then use a graphing utility to solve the systems. $$\left\\{\begin{array}{l}y=\frac{1}{3} x+\frac{2}{3} \\ y=\frac{5}{7} x-2\end{array}\right.$$

Read Exercise \(72 .\) Then use a graphing utility to solve the systems. $$\left\\{\begin{array}{l}y=-\frac{1}{2} x+2 \\ y=\frac{3}{4} x+7\end{array}\right.$$

In Exercises \(80-83,\) determine whether each statement is true or false. If the statement is false, make the necessary change(s) to produce a true statement. If \(A x+2 y=2\) and \(2 x+B y=10\) have graphs that intersect at \((2,-2),\) then \(A=-3\) and \(B=3\)

Perform the indicated operation. \(-3+(-9)\) (Section \(1.7,\) Table 1.7 )

In Exercises \(80-83,\) determine whether each statement is true or false. If the statement is false, make the necessary change(s) to produce a true statement. The equations \(y=x-1\) and \(x=y+1\) are dependent.

Perform the indicated operation. \(-3-(-9)\) (Section \(1.7,\) Table 1.7 )

Perform the indicated operation. \(-3(-9)\) (Section \(1.7,\) Table 1.7 )

Solve by expressing \(x\) and \(y\) in terms of \(a\) and \(b\) : $$ \left\\{\begin{array}{l} x-y=a \\ y=2 x+b \end{array}\right. $$

Will help you prepare for the material covered in the next section. In each exercise, solve the given equation. $$4 x-3(-x-1)=24$$

The point of intersection of the graphs of the equations \(A x-3 y=16\) and \(3 x+B y=7\) is \((5,-2) .\) Find \(A\) and \(B\)

Will help you prepare for the material covered in the next section. In each exercise, solve the given equation. $$5(2 y-3)-4 y=9$$

For which number is 5 times the number equal to the number increased by \(40 ?\) (Section \(2.5,\) Example 1 )

Will help you prepare for the material covered in the next section. In each exercise, solve the given equation. $$(5 x-1)+1=5 x+5$$

In which quadrant is \(\left(-\frac{3}{2}, 15\right)\) located? (Section 3.1, Example 1)

Solve: \(29,700+150 x=5000+1100 x\)

Exercises \(89-91\) will help you prepare for the material covered in the next section. The sum of two numbers, \(x\) and \(y,\) is \(28 .\) The difference between the numbers is 6 a. Write a system of linear equations that models these conditions. b. Solve the system and find the numbers.

If a slice of cheese contains \(x\) calories and a glass of wine contains \(y\) calories, write an algebraic expression for the number of calories in 3 slices of cheese and 2 glasses of wine.

A telephone plan has a monthly fee of \(\$ 20\) with a charge of \(\$ 0.05\) per minute. a. What is the total monthly cost for the plan if there are 200 minutes of calls? b. Write a formula that describes the total monthly cost of the plan, \(y,\) for \(x\) minutes of calls.