Page 250 - Basic College Mathematics with Early Integers

S E C T I O N 3.5 I ADDING AND SUBTRACTING UNLIKE FRACTIONS 227

Solution:

1. UNDERSTAND. Read and reread the problem. The phrase “how much time
remains” tells us to subtract.
2. TRANSLATE.

flight time flight time
time
In words: is from Tucson minus already
remaining
to Phoenix passed
T T T T T
time 5 1
Translate: = -
remaining 12 4
3. SOLVE: The LCD is 12.

5 1 5 1 3
- = - #
12 4 12 4 3
5 3
= -
12 12
1
2 2 1
= = =
#
12 2 6 6
1
4. INTERPRET. Check the solution. State your conclusion: The remaining flight
1
time is of an hour.
6
Work Practice 11

Calculator Explorations Performing Operations on Fractions

Scientific Calculator Graphing Calculator

Many calculators have a fraction key, such as a b/c , that Graphing calculators also allow you to perform operations
allows you to enter fractions, perform operations on frac- on fractions and will give exact fractional results.The frac-
tions, and will give the result as a fraction. If your calcula- tion option on a graphing calculator may be found under
tor has a fraction key, use it to calculate the MATH menu. To perform the addition in the left
3 4 column, try the keystrokes
+
5 7
3 5 + 4 7 MATH ENTER
Enter the keystrokes
ENTER
3 a b/c 5 + 4 a b/c 7 =
The display should read
The display should read 1_6 | 35
3/5 + 4/7 Frac 41/35
N
6
which represents the mixed number 1 . Let’s write the
35 Use a calculator to add the following fractions. Give each
result as a fraction.To convert from mixed number notation
sum as a fraction.
to fractional notation,press
1 2 3 2 4 7
2 nd d/c 1. + 2. + 3. +
16 5 20 25 9 8
The display now reads 41 | 35 9 5 10 12 14 15
4. + 5. + 6. +
11 12 17 19 31 21
41
which represents , the sum in fractional notation.
35