M
Math Coach Amy
Amy Ferguson Moncure

SAT

System of Inequalities

A table represents the system when every point works.

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What to Remember

Type both inequalities

Type each inequality in Desmos.

The shaded overlap is the solution.

A point on a solid boundary line works.

One point at a time

Enter one point at a time. Turn on the label.

As soon as one point does not work, move on to the next table.

The first point can work when the next point does not.

A table represents the system when every point works.

Example

Which table represents the system?

y ≥ 12x − 1

y ≤ −13x + 4

A

x y
06
22
41
62

B

x y
01
22
42
62

C

x y
01
25
42
62

D

x y
00
22
42
82

In Desmos, type

y ≥ 12x − 1

y ≤ −13x + 4

Enter one point at a time. Turn on the label. As soon as one point does not work, move on to the next table.

Table A: (0, 6) does not work. Move on.

Desmos graph of the system. The labeled points (0, 1), (2, 2), (4, 2), (6, 2) are in the shaded overlap.

Every point in table B works: (0, 1), (2, 2), (4, 2), and (6, 2).

Table C: (0, 1) works. (2, 5) does not. Move on.

Table D: (0, 0), (2, 2), and (4, 2) work. (8, 2) does not. Move on.

A table represents the system when every point works.

Answer: B

Together

Together

Work these three in a session. Enter one point at a time in Desmos.

1

Which table represents the system?

y ≥ 23x − 1

y ≤ −13x + 5

A

x y
−30
02
32
63

B

x y
02
36
63
−30

C

x y
01
32
63
93

D

x y
0−3
32
63
−31
Show Answer

In Desmos, type

y ≥ 23x − 1

y ≤ −13x + 5

Enter one point at a time. Turn on the label. As soon as one point does not work, move on to the next table.

Desmos graph of the system. The labeled points (−3, 0), (0, 2), (3, 2), (6, 3) are in the shaded overlap.

Every point in table A works: (−3, 0), (0, 2), (3, 2), and (6, 3).

Table B: (0, 2) works. (3, 6) does not. Move on.

Table C: (0, 1), (3, 2), and (6, 3) work. (9, 3) does not. Move on.

Table D: (0, −3) does not work. Move on.

A table represents the system when every point works.

Answer: A

2

Which table represents the system?

y ≥ −34x − 1

y ≤ 14x + 3

A

x y
05
40
8−1
−42

B

x y
01
46
80
−42

C

x y
−42
01
40
8−1

D

x y
00
40
8−1
46
Show Answer

In Desmos, type

y ≥ −34x − 1

y ≤ 14x + 3

Enter one point at a time. Turn on the label. As soon as one point does not work, move on to the next table.

Table A: (0, 5) does not work. Move on.

Table B: (0, 1) works. (4, 6) does not. Move on.

Desmos graph of the system. The labeled points (−4, 2), (0, 1), (4, 0), (8, −1) are in the shaded overlap.

Every point in table C works: (−4, 2), (0, 1), (4, 0), and (8, −1).

Table D: (0, 0), (4, 0), and (8, −1) work. (4, 6) does not. Move on.

A table represents the system when every point works.

Answer: C

3

Which table represents the system?

y ≥ 14x − 2

y ≤ −12x + 4

A

x y
0−4
40
80
−40

B

x y
01
44
80
−41

C

x y
−40
01
40
120

D

x y
−40
01
40
80
Show Answer

In Desmos, type

y ≥ 14x − 2

y ≤ −12x + 4

Enter one point at a time. Turn on the label. As soon as one point does not work, move on to the next table.

Table A: (0, −4) does not work. Move on.

Table B: (0, 1) works. (4, 4) does not. Move on.

Table C: (−4, 0), (0, 1), and (4, 0) work. (12, 0) does not. Move on.

Desmos graph of the system. The labeled points (−4, 0), (0, 1), (4, 0), (8, 0) are in the shaded overlap.

Every point in table D works: (−4, 0), (0, 1), (4, 0), and (8, 0).

A table represents the system when every point works.

Answer: D

Independent

Independent Practice

Try these five on your own. Enter one point at a time in Desmos.

1

Which table represents the system?

y ≥ −12x − 1

y ≤ 13x + 2

A

x y
04
31
60
−31

B

x y
−31
00
31
60

C

x y
00
35
60
−31

D

x y
00
31
60
−60
Show Answer

In Desmos, type

y ≥ −12x − 1

y ≤ 13x + 2

Enter one point at a time. Turn on the label. As soon as one point does not work, move on to the next table.

Table A: (0, 4) does not work. Move on.

Desmos graph of the system. The labeled points (−3, 1), (0, 0), (3, 1), (6, 0) are in the shaded overlap.

Every point in table B works: (−3, 1), (0, 0), (3, 1), and (6, 0).

Table C: (0, 0) works. (3, 5) does not. Move on.

Table D: (0, 0), (3, 1), and (6, 0) work. (−6, 0) does not. Move on.

A table represents the system when every point works.

Answer: B

2

Which table represents the system?

y ≥ 32x − 2

y ≤ −12x + 4

A

x y
0−4
12
22
−20

B

x y
01
25
12
−20

C

x y
01
−22
22
42

D

x y
−40
−22
01
22
Show Answer

In Desmos, type

y ≥ 32x − 2

y ≤ −12x + 4

Enter one point at a time. Turn on the label. As soon as one point does not work, move on to the next table.

Table A: (0, −4) does not work. Move on.

Table B: (0, 1) works. (2, 5) does not. Move on.

Table C: (0, 1), (−2, 2), and (2, 2) work. (4, 2) does not. Move on.

Desmos graph of the system. The labeled points (−4, 0), (−2, 2), (0, 1), (2, 2) are in the shaded overlap.

Every point in table D works: (−4, 0), (−2, 2), (0, 1), and (2, 2).

A table represents the system when every point works.

Answer: D

3

Which table represents the system?

y ≥ 15x − 1

y ≤ −25x + 4

A

x y
−51
02
20
51

B

x y
02
54
−51
50

C

x y
−51
02
51
101

D

x y
06
20
51
−50
Show Answer

In Desmos, type

y ≥ 15x − 1

y ≤ −25x + 4

Enter one point at a time. Turn on the label. As soon as one point does not work, move on to the next table.

Desmos graph of the system. The labeled points (−5, 1), (0, 2), (2, 0), (5, 1) are in the shaded overlap.

Every point in table A works: (−5, 1), (0, 2), (2, 0), and (5, 1).

Table B: (0, 2) works. (5, 4) does not. Move on.

Table C: (−5, 1), (0, 2), and (5, 1) work. (10, 1) does not. Move on.

Table D: (0, 6) does not work. Move on.

A table represents the system when every point works.

Answer: A

4

Which table represents the system?

y ≥ −23x + 1

y ≤ 13x + 3

A

x y
00
30
62
91

B

x y
02
36
62
91

C

x y
02
30
62
91

D

x y
02
30
62
−32
Show Answer

In Desmos, type

y ≥ −23x + 1

y ≤ 13x + 3

Enter one point at a time. Turn on the label. As soon as one point does not work, move on to the next table.

Table A: (0, 0) does not work. Move on.

Table B: (0, 2) works. (3, 6) does not. Move on.

Desmos graph of the system. The labeled points (0, 2), (3, 0), (6, 2), (9, 1) are in the shaded overlap.

Every point in table C works: (0, 2), (3, 0), (6, 2), and (9, 1).

Table D: (0, 2), (3, 0), and (6, 2) work. (−3, 2) does not. Move on.

A table represents the system when every point works.

Answer: C

5

Which table represents the system?

y ≥ 25x − 2

y ≤ −15x + 3

A

x y
05
20
51
−51

B

x y
−5−2
0−1
21
50

C

x y
02
54
20
−51

D

x y
−51
02
51
102
Show Answer

In Desmos, type

y ≥ 25x − 2

y ≤ −15x + 3

Enter one point at a time. Turn on the label. As soon as one point does not work, move on to the next table.

Table A: (0, 5) does not work. Move on.

Desmos graph of the system. The labeled points (−5, −2), (0, −1), (2, 1), (5, 0) are in the shaded overlap.

Every point in table B works: (−5, −2), (0, −1), (2, 1), and (5, 0).

Table C: (0, 2) works. (5, 4) does not. Move on.

Table D: (−5, 1), (0, 2), and (5, 1) work. (10, 2) does not. Move on.

A table represents the system when every point works.

Answer: B

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