* Evaluate square roots. * Use the product rule to simplify square roots. * Use the quotient rule to simplify square roots. * Add and subtract square roots. * Rationalize denominators. * Use rational roots.

1. 1.3 Radicals and Rational
Exponents
Chapter 1 Prerequisites

2. Concepts & Objectives
⚫ Objectives for this section:
⚫ Evaluate square roots.
⚫ Use the product rule to simplify square roots.
⚫ Use the quotient rule to simplify square roots.
⚫ Add and subtract square roots.
⚫ Rationalize denominators.
⚫ Use rational roots.

3. Evaluating Square Roots
⚫ When a number is squared, the square root of that is the
original number.
⚫ For example: Since 42 = 16, the square root of 16 is 4.
⚫ The square root is the opposite of squaring, just as
subtraction is the opposite of addition. To undo
squaring, we take the square root.
⚫ In general terms, if a is a positive real number, then the
square root of a is a number that, when multiplied by
itself gives a.

4. Evaluating Square Roots (cont.)
⚫ Since the square root could be positive or negative
(because multiplying two negative numbers gives a
positive number), the principal square root is the
nonnegative number that when multiplied by itself
equals a.
⚫ The principal square root of a is written . The symbol
is called a radical, the term under the symbol is called
the radicand, and the entire expression is called a radical
expression.
a

5. Simplifying Square Roots
⚫ To simplify a square root, we rewrite it such that there
are no perfect squares in the radicand.
⚫ The product rule for simplifying square roots allows us to
rewrite the square root of a product as a product of
square roots, i.e. . (Or vice versa.)
⚫ To simplify a square root radical expression:
⚫ Factor any perfect squares from the radicand.
⚫ Write the radical expression as a product of radical
expressions.
⚫ Simplify
ab a b
= 

6. Simplifying Square Roots (cont.)
Example: Simplify
Example: Simplify
300
5 4
162a b

7. Simplifying Square Roots (cont.)
Example: Simplify
Example: Simplify
300
300 100 3
100 3
10 3
= 
= 
=
5 4
162a b

8. Simplifying Square Roots (cont.)
Example: Simplify
Example: Simplify
300
300 100 3
100 3
10 3
= 
= 
=
5 4
162a b
5 4 4 4
4 4
4 4
2 2
162 81 2
81 2
81 2
9 2
a b a a b
a b a
a b a
a b a
=    
= 
= 
=

9. Simplifying Square Roots (cont.)
⚫ We can also rewrite the square root of a quotient as a
quotient of square roots and vice versa.
⚫ Examples: Simplify the radical expressions.
5 5 5
36 6
36
= =
11 11
7
7
4 2
234 234
26
26
9 3
x y x y
x y
x y
x x
=
= =

10. Rationalizing Denominators
⚫ When an expression involving square root radicals is
written in simplest form, it cannot contain a radical in
the denominator. We can remove radicals from the
denominators of fractions using a process called
rationalizing the denominator.
⚫ Since multiplying by 1 does not change the value of a
number, we can multiply by a form of 1 that will
eliminate the radical from the denominator.
⚫ For a denominator containing a single term, multiply by
the radical in the denominator over itself, i.e., if the
denominator is , multiply by .
b c c
c

11. Adding/Subtracting Square Roots
⚫ We can add or subtract radical expressions only when
they have the same radicand and when they have the
same radical type such as square roots.
⚫ Example:
⚫ However, it is often possible to simplify radical
expressions, and that may change the radicand.
⚫ Example:
2 3 2 4 2
+ =
12 3 3 2 3 3 3 5 3
+ = + =

12. Rational Exponents
⚫ Using the power rules, we can see that (for n ≠ 0)
⚫ The definition of an can thus be extended to rational
values of n (fractions) by defining a1/n to be the nth root
of a, or the number whose nth power is a.
( ) ( )
1/
1/ 1
n n n
n
a a a a
= = =

13. Rational Exponents (cont.)
⚫ For a1/n, where n is a positive integer,
⚫ Remember order of operations!
a1/n, n Even If n is even, and if a > 0, then a1/n
is the principal nth root of a.
a1/n, n Odd, If n is odd, and a is any nonzero
real number, then a1/n is the
positive or negative nth root of a.
( )
1
1
2
2
100 100
−  −

14. Rational Exponents (cont.)
Examples: Evaluate each expression.
a) 361/2 b) –1251/3 c) (–625)1/4
d) –2251/2 e) 321/5

15. Rational Exponents (cont.)
Examples: Evaluate each expression.
a) 361/2 b) –1251/3 c) (–625)1/4
d) –2251/2 e) 321/5
6
= 5
= −
not a real number

16. Rational Exponents (cont.)
Examples: Evaluate each expression.
a) 361/2 b) –1251/3 c) (–625)1/4
d) –2251/2 e) 321/5
6
= 5
= −
not a real number
15
= − 2
=

17. Rational Exponents (cont.)
⚫ What about rational exponents where the numerator is
not 1?
⚫ The notation am/n must be defined so that all of the
previous rules for exponents still hold. For the power
rule to hold, (a1/n)m must equal am/n. Therefore, am/n
is defined as follows:
For all integers m, all positive integers n, and all
real numbers a for which a1/n is a real number,
( ) ( )
1
1
or
m
m m
m n
n n n
a a a a
= =

18. Rational Exponents (cont.)
⚫ There are two ways you can evaluate an am/n expression:
⚫ Mentally: am/n means the nth root of the mth power,
so 323/5 would mean the 5th root of 32, which is 2,
raised to the 3rd power: 23 = 8.
⚫ Calculator: Most calculators have either a ^ or a xy
button. Unless you are using something like Desmos
which formats it for you correctly, make sure you
put parentheses around the fraction. See next
slide for examples.

19. Rational Exponents and Calculators
⚫ Without parentheses ⚫ With parentheses
 ✓

20. Rational Exponents (cont.)
Examples: Evaluate each expression.
a) 1252/3
b) (–64)2/3
c) –813/2
d) (–4)5/2

21. Rational Exponents (cont.)
Examples: Evaluate each expression.
a) 1252/3
b) (–64)2/3
c) –813/2
d) (–4)5/2
2
5 25
= =
( )
2
4 16
= − =
3
9 729
= − = −
( )
1/2
not a real number because 4 is not real
−

22. Simplifying Rational Exponents
Examples: Simplify.
a)
b)
c)
2/3 1/2
6 2
y y
( )
2/3 7/3 1/3
2
m m m
+
2 2/3
5/6 3
3/4 6
3 8
v y
y v
   
   
   
2 1
3 2
12y
+
=

23. Simplifying Rational Exponents
Examples: Simplify.
a)
b)
c)
2/3 1/2
6 2
y y
( )
2/3 7/3 1/3
2
m m m
+
2 2/3
5/6 3
3/4 6
3 8
v y
y v
   
   
   
2 1
3 2
12y
+
=
4 3
7/6
6 6
12 12
y y
+
= =

24. Simplifying Rational Exponents
Examples: Simplify.
a)
b)
c)
2/3 1/2
6 2
y y
( )
2/3 7/3 1/3
2
m m m
+
2 2/3
5/6 3
3/4 6
3 8
v y
y v
   
   
   
2 1
3 2
12y
+
=
4 3
7/6
6 6
12 12
y y
+
= =
2 7 2 1
3 3 3 3
2
m m
+ +
= +

25. Simplifying Rational Exponents
Examples: Simplify.
a)
b)
c)
2/3 1/2
6 2
y y
( )
2/3 7/3 1/3
2
m m m
+
2 2/3
5/6 3
3/4 6
3 8
v y
y v
   
   
   
2 1
3 2
12y
+
=
4 3
7/6
6 6
12 12
y y
+
= =
2 7 2 1
3 3 3 3
2
m m
+ +
= +
9 3
3
3 3
2 2
m m m m
= + = +

26. Simplifying Rational Exponents
Examples: Simplify.
a)
b)
c)
2/3 1/2
6 2
y y
( )
2/3 7/3 1/3
2
m m m
+
2 2/3
5/6 3
3/4 6
3 8
v y
y v
   
   
   
2 1
3 2
12y
+
=
4 3
7/6
6 6
12 12
y y
+
= =
2 7 2 1
3 3 3 3
2
m m
+ +
= +
9 3
3
3 3
2 2
m m m m
= + = +
5/3 2
3/2 4
9 4
v y
y v
  
=   
  
5 3
4 2
3 2
36v y
− −
=

27. Simplifying Rational Exponents
Examples: Simplify.
a)
b)
c)
2/3 1/2
6 2
y y
( )
2/3 7/3 1/3
2
m m m
+
2 2/3
5/6 3
3/4 6
3 8
v y
y v
   
   
   
2 1
3 2
12y
+
=
4 3
7/6
6 6
12 12
y y
+
= =
2 7 2 1
3 3 3 3
2
m m
+ +
= +
9 3
3
3 3
2 2
m m m m
= + = +
5/3 2
3/2 4
9 4
v y
y v
  
=   
  
5 3
4 2
3 2
36v y
− −
=
5 12 4 3
3 3 2 2
36v y
− −
=
1/2
7/3 1/2
7/3
36
36
y
v y
v
−
= =

28. Classwork
1.3: 8-32 (×4); 1.2: 26-42 (even); 1.1: 54-68
⚫ 1.3 Classwork Check
⚫ Quiz 1.2