2.1 Linear Equations in Two Variables
1. Estimate the slope of the line.
y
5
4
3
2
1
–5
–4
–3
–2
–1
–1
1
2
3
4
x
5
–2
–3
–4
–5
a.
b.
c.
d.
e.
1.5
4.5
2.5
3.5
Undefined
ANS: A
PTS: 1
REF: 2.1.13
2. Find the slope and y-intercept (if possible) of the equation of the line. Sketch the line.
a.
d.
y
–5
b.
–4
–3
–2
y
5
5
4
4
3
3
2
2
1
1
–1
–1
1
2
3
4
5
x
–5
–4
–3
–2
–1
–1
–2
–2
–3
–3
–4
–4
–5
–5
7
y-intercept: (0, 5)
–5
y-intercept: (0, 5)
e.
1
2
3
4
5
x
y
–5
–4
–3
–2
y
5
5
4
4
3
3
2
2
1
1
–1
–1
1
2
3
4
5
x
–5
–4
–3
–2
–1
–1
–2
–2
–3
–3
–4
–4
–5
–5
–7
y-intercept: (0, 5)
m is undefined.
y-intercept: (0, 5)
1
2
3
4
5
x
c.
y
5
4
3
2
1
–5
–4
–3
–2
–1
–1
1
2
3
4
5
x
–2
–3
–4
–5
5
y-intercept: (0, 5)
ANS: A
PTS: 1
REF: 2.1.17
3. Find the slope and y-intercept (if possible) of the equation of the line. Sketch the line.
a.
d.
y
–5
–4
–3
–2
y
5
5
4
4
3
3
2
2
1
1
–1
–1
1
2
3
4
5
x
–5
–4
–3
–2
–1
–1
–2
–2
–3
–3
–4
–4
–5
–5
5
y-intercept: (0, 5)
–5
y-intercept: (0, 5)
b.
1
2
3
4
5
x
1
2
3
4
5
x
e.
y
–5
–4
–3
–2
y
5
5
4
4
3
3
2
2
1
1
–1
–1
1
2
3
4
5
x
–5
–3
–4
–4
–5
–5
m is undefined.
y-intercept: (0, 5)
5
4
3
2
1
–2
–1
–1
1
2
3
4
5
x
–2
–3
–4
–5
–1
y-intercept: (0, 5)
ANS: B
–1
–1
–3
y
–3
–2
–2
c.
–4
–3
–2
1
y-intercept: (0, –5)
–5
–4
PTS: 1
REF: 2.1.18
4. Find the slope and y-intercept (if possible) of the equation of the line. Sketch the line.
a.
d.
y
–10 –8
–6
–4
y
10
10
8
8
6
6
4
4
2
2
–2
–2
2
4
6
8
10
x
–10 –8
–6
–4
–2
–2
–4
–4
–6
–6
–8
–8
–10
–10
2
4
6
8
10
x
2
4
6
8
10
x
m is undefined.
y-intercept: (0, 4)
y-intercept: (0, 4)
b.
e.
y
–10 –8
c.
–6
–4
y
10
10
8
8
6
6
4
4
2
2
–2
–2
2
4
6
8
10
x
–10 –8
–6
–4
–2
–2
–4
–4
–6
–6
–8
–8
–10
–10
–1
y-intercept: (0, 6)
6
y-intercept: (0, 6)
y
10
8
6
4
2
–10 –8
–6
–4
–2
–2
2
4
6
8
10
x
–4
–6
–8
–10
–6
y-intercept: (0, 6)
ANS: D
PTS: 1
REF: 2.1.19
5. Find the slope and y-intercept (if possible) of the equation of the line. Sketch the line.
a.
d.
y
–5
–4
–3
–2
y
5
5
4
4
3
3
2
2
1
1
–1
–1
1
2
3
4
5
x
–5
–3
–2
–1
–1
–2
–2
–3
–3
–4
–4
–5
–5
–3
y-intercept: (0,5)
m is undefined.
There is no y-intercept.
b.
–4
e.
1
2
3
4
5
x
y
–5
–4
–3
–2
y
5
5
4
4
3
3
2
2
1
1
–1
–1
1
2
3
4
5
x
–5
–4
–3
–2
–1
–1
–2
–2
–3
–3
–4
–4
–5
–5
m is undefined.
There is no y-intercept.
1
2
3
4
5
x
m is undefined.
There is no y-intercept.
c.
y
5
4
3
2
1
–5
–4
–3
–2
–1
–1
1
2
3
4
5
x
–2
–3
–4
–5
–5
y-intercept: (0,3)
ANS: B
PTS: 1
REF: 2.1.21
6. Find the slope and y-intercept (if possible) of the equation of the line. Sketch the line.
a.
d.
y
y
–5
–4
–3
–2
5
5
4
4
3
3
2
2
1
1
–1
–1
1
2
3
4
5
x
–5
–4
–3
–2
–1
–1
–2
–2
–3
–3
–4
–4
–5
–5
m is Undefined.
0
8
y-intercept: (0, )
5
8
y-intercept: (0, )
5
b.
1
2
3
4
5
x
1
2
3
4
5
x
e.
y
–5
–4
–3
–2
y
5
5
4
4
3
3
2
2
1
1
–1
–1
1
2
3
4
5
x
–1
–1
–3
–4
–4
–5
–5
There is no y-intercept.
y
4
3
2
1
–2
–2
–3
5
–3
–3
–2
c.
–4
–4
–2
–5
y-intercept: (0, 8)
–5
–5
–1
–1
–2
–3
–4
–5
–8
y-intercept: (0, 5)
1
2
3
4
5
x
ANS: D
PTS: 1
REF: 2.1.22
7. Find the slope and y-intercept (if possible) of the equation of the line. Sketch the line.
a.
d.
y
y
7
7
6
6
5
5
4
4
3
3
2
2
1
1
–7 –6 –5 –4 –3 –2 –1
–1
1
2
3
4
5
6
7
x
–7 –6 –5 –4 –3 –2 –1
–1
–2
–2
–3
–3
–4
–4
–5
–5
–6
–6
–7
–7
–3
y-intercept: (0, 7)
0
y-intercept: (0, 7)
b.
2
3
4
5
6
7
x
1
2
3
4
5
6
7
x
e.
y
y
7
7
6
6
5
5
4
4
3
3
2
2
1
1
–7 –6 –5 –4 –3 –2 –1
–1
1
2
3
4
5
6
7
x
–7 –6 –5 –4 –3 –2 –1
–1
–2
–2
–3
–3
–4
–4
–5
–5
–6
–6
–7
–7
–7
y-intercept: (0, 3)
c.
1
m is Undefined.
7
y-intercept: (0, )
3
y
7
6
5
4
3
2
1
–7 –6 –5 –4 –3 –2 –1
–1
1
2
3
4
5
6
7
x
–2
–3
–4
–5
–6
–7
There is no y-intercept.
ANS: D
PTS: 1
REF: 2.1.25
8. Find the slope and y-intercept (if possible) of the equation of the line. Sketch the line.
a.
d.
y
–5
–4
–3
–2
y
5
5
4
4
3
3
2
2
1
1
–1
–1
1
2
3
4
5
x
–5
–3
–2
–1
–1
–2
–2
–3
–3
–4
–4
–5
–5
m is Undefined.
There is no y-intercept.
b.
–4
0
y-intercept: (0,–5)
e.
1
2
3
4
5
x
y
y
–5
–4
–3
–2
5
5
4
4
3
3
2
2
1
1
–1
–1
1
2
3
4
5
x
–5
–4
–3
–2
–1
–1
–2
–2
–3
–3
–4
–4
–5
–5
0
y-intercept: (0,–5)
1
2
3
4
5
x
There is no y-intercept.
c.
y
5
4
3
2
1
–5
–4
–3
–2
–1
–1
1
2
3
4
5
x
–2
–3
–4
–5
0
y-intercept: (0,5)
ANS: D
PTS: 1
REF: 2.1.26
9. Find the slope and y-intercept (if possible) of the equation of the line. Sketch the line.
a.
d.
y
–5
–4
–3
–2
y
5
5
4
4
3
3
2
2
1
1
–1
–1
1
2
3
4
5
x
–5
–4
–3
–2
–1
–1
–2
–2
–3
–3
–4
–4
–5
–5
m is undefined.
There is no y-intercept.
1
2
3
4
5
x
2
3
4
5
x
m is undefined.
There is no y-intercept.
b.
e.
y
–5
–4
–3
–2
y
5
5
4
4
3
3
2
2
1
1
–1
–1
1
2
3
4
5
x
–5
–3
–4
–4
–5
–5
4
3
2
1
–1
–1
1
2
3
4
5
x
–2
–3
–4
–5
–4
y-intercept: (0,3)
ANS: D
1
m is undefined.
There is no y-intercept.
5
–2
–1
–1
–3
y
–3
–2
–2
c.
–4
–3
–2
–3
y-intercept: (0,4)
–5
–4
PTS: 1
REF: 2.1.27
10. Plot the points and find the slope of the line passing through the pair of points.
(0, 6), (4, 0)
a.
d.
y
–10 –8
–6
–4
y
10
10
8
8
6
6
4
4
2
2
–2
–2
2
4
6
8
10
x
–10 –8
–6
–4
–2
–2
–4
–4
–6
–6
–8
–8
–10
–10
3
4
–
b.
4
6
8
10
x
2
4
6
8
10
x
2
3
e.
y
–10 –8
–
c.
2
3
2
–6
–4
y
10
10
8
8
6
6
4
4
2
2
–2
–2
2
4
6
8
10
x
–10 –8
–6
–4
–2
–2
–4
–4
–6
–6
–8
–8
–10
–10
3
2
y
10
8
6
4
2
–10 –8
–6
–4
–2
–2
2
4
6
8
10
x
–4
–6
–8
–10
–
3
2
ANS: B
PTS: 1
REF: 2.1.29
11. Plot the points and find the slope of the line passing through the pair of points.
(11, 0), ( 0, –9)
a.
d.
y
y
15
15
12
12
9
9
6
6
3
3
(11, 0)
–15 –12 –9 –6 –3
–3
3
6
9
12 15
(11, 0)
x
–15 –12 –9 –6 –3
–3
–6
–9
–
b.
3
–6
–9
(0, –9)
–12
–12
–15
–15
11
9
11
9
e.
(0, –9)
6
9
12 15
x
y
y
15
15
12
12
9
9
6
6
3
3
(–7, 0)
(11, 0)
–15 –12 –9 –6 –3
–3
3
6
9
12 15
x
–15 –12 –9 –6 –3
–3
3
6
9
–6
–6
–9
(0, 13)
–9
(0, –9)
–12
–12
–15
–15
9
11
7
13
c.
y
15
12
(0, 11)
9
6
3
(–9, 0)
–15 –12 –9 –6 –3
–3
3
6
9
12 15
x
–6
–9
–12
–15
–
9
11
ANS: B
PTS: 1
REF: 2.1.30
12. Plot the points and find the slope of the line passing through the pair of points.
(–2, –9), ( 3, 5)
a.
d.
12 15
x
y
y
15
15
12
12
9
9
6
(4, 6)
6
(3, 5)
3
3
–15 –12 –9 –6 –3
–3
3
6
9
12 15
x
–15 –12 –9 –6 –3
–3
–6
–6
(–2, –9) –9
(–1, –8)–9
–12
–12
–15
–15
4
–
b.
3
6
9
12 15
x
14
5
e.
y
y
15
15
12
12
9
9
6
6
(3, 5)
3
3
–15 –12 –9 –6 –3
–3
3
6
9
12 15
x
–15 –12 –9 –6 –3
–3
(–18, –4)
–6
–9
–12
–12
–15
–15
14
5
5
14
c.
y
15
12
(7, 12)
9
6
3
(–18, –4)
3
6
9
12 15
x
–6
–9
–12
–15
–
5
14
ANS: B
–6
(–2, –9) –9
–15 –12 –9 –6 –3
–3
(7, 12)
PTS: 1
REF: 2.1.31
3
6
9
12 15
x
13. Plot the points and find the slope of the line passing through the pair of points.
(9, –4), ( 1, –4)
a.
y
d.
y
15
15
12
12
9
9
6
6
3
3
–15 –12 –9 –6 –3
–3
–15 –12 –9 –6 –3
–3
–6
3
6
9
(1, –4)
12 15
x
3
9
(1, –4)
–6
(9, –4)
6
x
12 15
(9, –4)
–9
–9
–12
–12
–15
–15
m
is undefined
0
b.
e.
y
y
15
15
12
12
9
9
6
6
3
3
(9, 0)
–15 –12 –9 –6 –3
–3
–6
–
c.
1
9
3
(1, –4)
6
9
12 15
x
–15 –12 –9 –6 –3
–3
(9, –4)
–6
–9
–9
–12
–12
–15
–15
1
9
3
(0, –4)
6
9
12 15
x
y
15
12
9
6
3
–15 –12 –9 –6 –3
–3
–6
3
6
9
(1, –4)
12 15
x
(9, –4)
–9
–12
–15
4
5
ANS: A
PTS: 1
REF: 2.1.33
14. Plot the points and find the slope of the line passing through the pair of points.
(4, 8), ( 8,–8)
a.
d.
y
y
15
15
12
9
6
6
3
3
6
9
12 15
x
–15 –12 –9 –6 –3
–3
–6
–6
–9
–9
–12
–12
–15
–15
4
b.
(12, 11)
9
(2, 8)
3
–15 –12 –9 –6 –3
–3
(8, 12)
12
(5, 9)
3
e.
3
6
9
12 15
x
y
y
15
15
12
12
9
6
6
3
3
3
6
(8, 12)
9
(4, 8)
–15 –12 –9 –6 –3
–3
(12, 12)
9
x
12 15
–15 –12 –9 –6 –3
–3
3
6
9
–6
–6
(8, –8)
–9
–9
–12
–12
–15
–15
4
3
c.
y
15
12
(4, 8)
9
6
(1, 7)
3
–15 –12 –9 –6 –3
–3
3
6
9
x
12 15
–6
–9
–12
–15
3
ANS: B
PTS: 1
REF: 2.1.32
15. Plot the points and find the slope of the line passing through the pair of points.
(0, –9), (–6, 0)
y
a.
d.
10
8
6
4
2
(–6, 0)
–10 –8
–6
–4
–2
–2
2
–4
–6
–8
–10
(0, –9)
4
6
8
10
x
12 15
x
y
3
2
10
8
6
4
2
(–8, 0)
–10 –8
–6
–4
–2
–2
2
4
6
8
10
x
4
6
8
10
x
–4
–6
–8
–10
(0, –11)
4
7
b.
e.
y
y
10
10
8
8
6
6
4
4
2
2
(–9, 0)
–10 –8
(–6, 0)
–6
–4
–2
–2
2
4
6
8
10
x
–10 –8
–4
–6
–8
–8
–10
–10
3
2
c.
y
10
8
6
4
2
(–9, 0)
–4
–2
–2
2
4
6
8
10
x
–4
–6
(0, –6)
–8
–10
–
3
2
ANS: E
–2
–2
2
–6
(0, –6)
–
–6
–4
–4
3
2
–10 –8
–6
PTS: 1
REF: 2.1.36
(0, –9)
16. Plot the points and find the slope of the line passing through the pair of points.
(4.1, 3.1), ( –2.8, 4.1)
a.
d.
y
(–1.8, 5.1)
y
15
15
12
12
9
9
6
6
(–2.8, 4.1)
(5.1, 4.1)
3
–15 –12 –9 –6 –3
–3
3
6
9
12 15
x
3
(4.1, 3.1)
–15 –12 –9 –6 –3
–3
–6
–6
–9
–9
–12
–12
–15
–15
3
6
9
12 15
x
12 15
x
–0.14
0.26
b.
e.
y
y
15
15
12
12
(7.1, 8.1)
9
9
6
6
3
(–2.8, 4.1)
(8.1, 1.2)
–15 –12 –9 –6 –3
–3
3
6
9
12 15
x
3
–15 –12 –9 –6 –3
–3
–6
–6
–9
–9
–12
–12
–15
–15
–6.9
5.54
c.
y
15
12
(7.1, 8.1)
9
6
3
–15 –12 –9 –6 –3
–3
–6
–9
–12
–15
(8.1, 1.2)
3
6
9
12 15
x
(4.1, 3.1)
3
6
9
0.66
ANS: D
PTS: 1
REF: 2.1.39
17. Find the slope-intercept form of the equation of the line that passes through the given point
and has the indicated slope m. Sketch the line.
(0,–4),
a.
d.
y
10
8
y
10
6
8
4
6
2
4
–10 –8
2
–10 –8
–6
–4
–2
–2
2
4
6
8
10
–6
–4
–2
–2
2
4
6
8
x
10
–4
x
–6
–4
–8
–6
–10
–8
–10
b.
e.
y
10
8
y
10
6
8
4
6
2
4
–10 –8
2
–10 –8
–6
–4
–2
–2
4
6
8
10
x
–4
–2
–2
–4
–6
–4
–8
–6
–10
–8
–10
c.
2
–6
2
4
6
8
10
x
y
10
8
6
4
2
–10 –8
–6
–4
–2
–2
2
4
6
8
10
x
–4
–6
–8
–10
ANS: B
PTS: 1
REF: 2.1.51
18. Find the slope-intercept form of the equation of the line that passes through the given point
and has the indicated slope m. Sketch the line.
a.
d.
y
10
8
y
6
10
4
8
2
6
4
–10 –8
–6
–4
–2
–2
2
4
6
8
10
x
2
–4
–6
–10 –8
–6
–4
–2
–2
–8
–4
–10
–6
–8
–10
b.
e.
2
4
6
8
10
x
y
y
–10 –8
–6
–4
10
10
8
8
6
6
4
4
2
2
–2
–2
2
4
6
8
10
x
–10 –8
–6
–4
–2
–2
–4
–4
–6
–6
–8
–8
–10
–10
2
4
6
c.
y
10
8
6
4
2
–10 –8
–6
–4
–2
–2
2
4
6
8
10
x
–4
–6
–8
–10
ANS: D
PTS: 1
REF: 2.1.53
19. Find the slope-intercept form of the equation of the line that passes through the given point and has the
indicated slope m.Sketch the line.
a.
d.
8
10
x
y
–10 –8
–6
–4
y
10
10
8
8
6
6
4
4
2
2
–2
–2
2
4
6
8
10
x
–10 –8
–6
–4
–2
–2
–4
–4
–6
–6
–8
–8
–10
–10
b.
2
4
6
8
10
x
2
4
6
8
10
x
e.
y
–10 –8
–6
–4
y
10
10
8
8
6
6
4
4
2
2
–2
–2
2
4
6
8
10
x
–10 –8
–6
–4
–2
–2
–4
–4
–6
–6
–8
–8
–10
–10
c.
y
10
8
6
4
2
–10 –8
–6
–4
–2
–2
2
4
6
8
10
x
–4
–6
–8
–10
ANS: D
PTS: 1
REF: 2.1.54
20. Find the slope-intercept form of the equation of the line that passes through the given point
and has the indicated slope m. Sketch the line.
m is undefined.
a.
d.
y
10
y
10
8
8
6
6
4
4
2
2
–10 –8
–10 –8
–6
–4
–2
–2
2
4
6
8
10
–6
–4
–2
–2
2
4
6
8
10
x
2
4
6
8
10
x
x
–4
–4
–6
–6
–8
–8
–10
–10
b.
e.
y
–10 –8
–6
–4
y
10
10
8
8
6
6
4
4
2
2
–2
–2
2
4
6
8
10
x
–2
–2
–4
–6
–8
–8
–10
–10
y
8
6
4
2
–4
–4
–6
10
–6
–6
–4
c.
–10 –8
–10 –8
–2
–2
–4
–6
–8
–10
2
4
6
8
10
x