Download 8.1 Just Like Fractions, Multiply and Divide

Algebra 2
HS Mathematics
Unit: 08 Lesson: 02
Just Like Fractions (Multiply & Divide)
Explain how to make each fraction computation. Then follow a similar procedure for the operations
with rational expressions.
Fractions
1.
3
4
Steps
Operations with Rational Expressions
2
x


x  4 x 1
 57 
3
2.
2  94 
8

x6
( x  1) 
8

x6
x  3 2x


x 1 x  3
 41 
3.
4
9
4.
4
15
5.
2
3
 81 
2x  4
5


x 3 x 2
6.
3
2
 81 
4
x 7
 2

x  3 x  4x  3
x 3
x 5


x  9 x  20 2 x  6
 56 
2
Remember!
When can you simplify a fraction (or a rational algebraic expression)?
©2010, TESCCC
08/01/10
Algebra 2
HS Mathematics
Unit: 08 Lesson: 02
Just Like Fractions (Multiply & Divide) KEY
Explain how to make each fraction computation. Then follow a similar procedure for the operations
with rational expressions.
Fractions
1.
2.
3
4
 57  15/28
2  94  8/9
Steps
Multiply “across”
(Multiply the numerators
and multiply the
denominators)
Put the whole number part
over “1”, then multiply
across
Operations with Rational Expressions
2
x


x  4 x 1
2x
x2-3x-4
8

x6
24
x+6
3
( x  1) 
3.
4.
4
9
 41  1/9
4
15
 56  2/9
Simplify by “canceling” the
factors on top and bottom.
Then multiply across.
Simplify first by “canceling”
the common factors on top
and bottom. Then multiply
across.
8

x6
x  3 2x


x 1 x  3
8x+8
x+6
2x
x-1
x 3
x 5


x  9 x  20 2 x  6
1
2x+8
2x  4
5


x 3 x 2
2x2-8
5x+15
x 7
4
 2

x  3 x  4x  3
4x+4
x-7
2
Multiply by the reciprocal
5.
6.
2
3
3
2
 81  16/3
 81  12
Change times to
multiplication by the
reciprocal. Then simplify
common factors, and
multiply.
Remember!
When can you simplify a fraction (or a rational algebraic expression)?
Only when it’s multiplication.
Only when the numerator and denominator have common factors.
©2010, TESCCC
08/01/10