Write an equation for each line passing through the given pair of points. Give the final
answer in (a)slope-intercept form and (b)standard form. See Example 7.
- and 66. and 67. and
- and 69. and 70. and
- and 72. and
Write an equation of the line satisfying the given conditions. Give the final answer in slope-
intercept form.(Hint:Recall the relationships among slopes of parallel and perpendicular lines
in Section 3.3.)
73.Perpendicular to y-intercept
74.Parallel to y-intercept
75.Through parallel to
76.Through perpendicular to
77.Through parallel to
78.Through perpendicular to
The cost y of producing x items is, in some cases, expressed as The number b
gives thefixed cost(the cost that is the same no matter how many items are produced), and
the number m is thevariable cost(the cost of producing an additional item). Use this infor-
mation to work Exercises 79 and 80.
79.It costs $400 to start up a business selling snow cones. Each snow cone costs $0.25 to
produce.
(a)What is the fixed cost?
(b)What is the variable cost?
(c) Write the cost equation.
(d)What will be the cost of producing 100 snow cones, based on the cost equation?
(e) How many snow cones will be produced if the total cost is $775?
80.It costs $2000 to purchase a copier, and each copy costs $0.02 to make.
(a)What is the fixed cost?
(b)What is the variable cost?
(c) Write the cost equation.
(d)What will be the cost of producing 10,000 copies, based on the cost equation?
(e) How many copies will be produced if the total cost is $2600?
Solve each problem. See Example 8.
81.The table lists the average annual cost (in dollars) of tuition and fees at 2-year colleges
for selected years, where year 1 represents 2004, year 2 represents 2005, and so on.
y=mx+b.
1 - 1, 4 2 ; 2 x=- 3 y+ 8
1 2, - 32 ; 3 x= 4 y+ 5
1 4, 2 2 ; x- 3 y= 7
1 2, 3 2 ; 4 x-y=- 2
5 x-y= 10 ; 1 0, - 22
x- 2 y=7; 1 0, - 32
a-
1
4
,
5
4
a b
1
2
,
3
2
a b
1
3
,
7
3
a- b
2
3
,
8
3
b
1 0, - 22 1 - 3, 0 2 1 - 2, - 12 1 3, - 42 1 - 1, - 72 1 - 8, - 22
1 4, 10 2 1 6, 12 2 1 8, 5 2 1 9, 6 2 1 - 4, 0 2 1 0, 2 2
220 CHAPTER 3 Linear Equations and Inequalities in Two Variables; Functions
Source:The College Board.
Year Cost (in dollars)
1 2079
2 2182
3 2272
4 2361
5 2402
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