Rational Exponents

Lesson 6.4

Algebra II

HW: 6.4/10-66 multiples of 3

Radicals (also called roots) are directly related to exponents.

Rational Exponents

All radicals (roots) can be written in a different format without a radical symbol.

This different format uses a rational (fractional) exponent.

When the exponent of the radicand (expression under the radical symbol) is one, the rational exponent form of a radical looks like this:

Rational Exponents

Remember that the index, n, is a whole number equal to or greater than 2.

nn aa1

Rational Exponents

Examples:

• When a base has a fractional exponent, do not think of the exponent in the same way as when it is a whole number.

• When a base has a fractional exponent, the exponent is telling you that you have a radical written in a different form.

2

1

66 3

13 1111

base

Rational Exponents

For any exponent of the radicand, the rational exponent form of a radical looks like this:

n

mm

nn m aaa

How do you simplify ?

Rational Exponents

• You can rewrite the expression using a radical.

• Simplify the radical expression, if possible.

• Write your answer in simplest form.

• Reduce the rational exponent, if possible.

2

1

16

Rational Exponents

Example:

2

1

16 416

3

1

125 51253

Rational Exponents

Examples:

5

2

32 4232 225

3

5

64 1024464 553

Rational Exponents

Examples:

No real number solution 2

1

16 16

3

2

216 366216 223

Rational Exponents

The basic properties for integer exponents also hold for rational exponents as long as the expression represents a real number.

Rational Exponents

Example:

What would the answer above be if you were to write it in radical form?

6

16

3

6

4

2

1

3

2

2

1

3

2

555

5

5

Rational Exponents

Example:

6

16

3

6

4

2

1

3

2

2

1

3

2

555

5

5

6 5

Rational Exponents

Do you remember the basic Rules of Exponents that you learned in Roots and Radicals?

See the next two slides for a quick review.

Multiplication Division

b may not be equal to 0.

The Square Root Rules (Properties)

Rational Exponents

b

a

b

ababa

Multiplication Division

b may not be equal to 0.

The Cube Root Rules (Properties)

Rational Exponents

33

3

b

a

b

a333 baba

Rational Exponents

The more general rules for any radical are as follows …

Multiplication Division

b may not be equal to 0.

The Rules (Properties)

Rational Exponents

nn

n

b

a

b

annn baba

Rational Exponents

These same rules in rational exponent form are as follows …

Multiplication Division

b may not be equal to 0.

The Rules (Properties)

Rational Exponents

nnn baba111

n

n

n

b

a

b

a1

1

1

Rational Exponents

In working with radicals, whether in radical form or in fractional exponent form, simplify wherever and whenever possible.

What is the process for simplifying radical expressions?

Rational Exponents

Simplifying radicals – A radical expression is in simplest form once ALL of the following conditions have been met.…

• the radicand (expression under the radical symbol) cannot

be written in an exponent form with any factor having an

exponent equal to or larger than the index of the radical;

• there is no fraction under the radical symbol;

• there is no radical in a denominator.

Rational Exponents

Examples – Simplifying Radical Expressions:

3 54 3 227 33 227 3 23

5

3

3 6

8

5

5

5

3

25

155

15

3 2

3 2

3 6

6

6

8

3 3

3 2

6

68 6

68 3 2

3

64 3 2