Chapter 4: Linear Inequalities Section 2: Using Algebra
Topics in Algebra 1 © 2001 Texas Instruments Teacher Notes 4-20
Activities
(continued)
Additional Problems
1. 6.4x > 16
when
x>2.5
2.
1
2
x
N
2
M
2
when
x
0
3. 2x
N
2.1 <
M
3.5
when
x <
M
0.7
4. Let C = the number of phone calls per month. Therefore, 15 + 0.25C
≤
30. The solution is
C
≤
60. Students could discuss that this is about 2 calls per day. They should write whether or
not this phone plan would be adequate for them.
³
Try-It!
é
on Your TI
.
83 Plus or TI
.
73
This keystroke exercise lets students learn about the logic functionality built in the calculator.
They see how to store a variable, test an inequality and finally graph a TRUE(
1
)/FALSE(
0
) graph.
By graphing the solution set using the calculator’s logic, they can verify their algebraic work on
the inequalities.
Students first solve the problem by hand. They should show all their work.
If
X=3
, is
2X+4>7
true or false?
Answer:
2(3) + 4 >7
6 + 4 >7
10>7
Therefore, the statement is true.
Tell students to follow the steps exactly on the calculators. Example screens are displayed on
the worksheets for students to compare with the calculator screens.
Additional Problems
Tell students to do the following calculation by hand, and then check the answers using the
calculator. They should show all their work.
The graphs are shown below using
ZDecimal
(
(
) window values. Students should discuss
how they determine the endpoint of the solution set. Remind them that using algebra gives the
exact answer. The graph helps them see where the solution is approximately located.
1.
2. 3.
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