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Think about it… What is 1/2 of …
12100120
What about ¼ of…
100
480
What are we really doing?
What multiplication problem goes with this model?
Put your answer in simplest form!
Remember!
To multiply fractions, first multiply the numerator, then
multiply the denominator.
Mutliply the numerator.
Multiply the denomiator
Simplify.
1 3
2 4
1
4__ • 2
5__
=
1 • 2
4 • 5
= 2
20__
= 1
10__
Multiply numerators. Multiply denominators.
The GCF of 2 and 20 is 2.
The answer is in simplest form.
5
7__ 4
15__•
_____
=
=
Use the GCF to simplify the fractions before multiplying. The greatest common factor of 5 and 15 is 5.
4
21__
1 • 4
7 • 3
5
7__ •
4
15__
Multiply numerators. Multiply denominators.
The answer is in simplest form.
1
7__ •
4
3__
1
3
=
Simplify first- Another method
4
9__ 6
10__• ______=
=
Multiply numerators. Multiply denominators.
24
90__
4 • 6
9 • 10
4
9__ •
6
10__
The GCF of 24 and 90 is 6.
The answer is in simplest form.=4
15__
Multiply. Write each answer in simplest form.
1. 2.
Evaluate the expression x • for each value of
x. Write the answer in simplest form.
3. x = 4. x =
5. At a particular college of the students take a
math class. Of these students, take basic algebra.
What fraction of all students take basic algebra?
3
5__1
4__ •
5
7__3
10__ •
1
8__
4
5__ 1
8__
2
5__
1
4__
3
20__ 3
14__
1
10__ 1
64__
1
10__
Reciprocals can help you divide by fractions. Two numbers are reciprocals if their product is 1.
RECIPROCALIOUS!
Find the reciprocal.
19__
19__ • = 1 Think: of what number is 1?
19__1
9__
19__ • 9 = 1 of is 1.
19__ 9
1__
The reciprocal of is 9.19__
÷ 710__
710__ ÷ = •
Rewrite as multiplication using the
reciprocal of , . 51__
Simplify before multiplying.
710__ 5
1__
7 • 510 • 1____ =
You can write the answer as a mixed number.
=
72__
15__
15__
15__
1
2
Multiply.
= 3 12__
÷ 3 23__
23__ ÷ 3 = •
Rewrite as multiplication using the
reciprocal of 3, . 13__
Multiply by the reciprocal.
23
__ 13__
2 • 13 • 3____ =
The answer is in simplest form.
=
29__
You TryComplete all 8 problems on
your notes
When you are done, raise your hand and then help others
around you
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