Vocabulary
 Radical Expression – expression that contains a
  radical, such as a square root, cube root, or other root.




 Simplest form of a radical expression:
    No perfect square factors are in the radicand.
    No fractions are in the radicand.
    No radicands appear in the denominator of a fraction.
Product Property of Radicals
 The square root of a product equals the product of the
 square roots of the factors.

 ab = a × b        where   a ³ 0 and b ³ 0

 4x = 4 × x = 2 x
Example 1            Use the product property of radicals

           =
a.   32         16 • 2              Factor using perfect square factor.
           =
                16 •     2          Product property of radicals
           =
               4 2                  Simplify.


                9 • x2 • x
           =
b.   9x3                            Factor using perfect square factors.

                9 •      x2 •
           =
                                x   Product property of radicals
           =
               3x x                 Simplify.
Example 2       Multiply radicals

     2• 8           2•8
            =
a.                                  Product property of radicals
            =
                    16              Multiply.
            =
                4                   Simplify.


     3x • 4 x       4 3x • x
                =
b.                                  Product property of radicals

                =
                    4 3x2           Multiply.

                    4• 3•
                =
                               x2   Product property of radicals
                =
                    4x 3            Simplify.
Example 2         Multiply radicals

     7xy2 • 3 x       3 7xy2 • x
                  =
c.                                       Product property of radicals
                  =
                      3 7x2y2            Multiply.

                      3• 7•     x2 • y2 Product property of radicals
                  =

                  =
                      3xy 7              Simplify.
Quotient Property of Radicals
 The square root of a quotient equals the quotient of
 the square roots of the numerator and denominator.

        a   a
          =         where   a ³ 0 and b > 0
        b   b

        16   16 4
           =   =
        25   25 5
Example 3         Use the quotient property of radicals

a.   13        13                 Quotient property of radicals
         =
     100      100

              13
         =                        Simplify.
              10


b.   7        7
       2
         =                        Quotient property of radicals
     x       x2

              7                   Simplify.
        =
             x
Rationalizing the denominator
 The process of eliminating a radical from an
 expression’s denominator is called rationalizing the
 denominator.
Example 4                  Rationalize the denominator

     5            5          7                        7
a.        =            •                Multiply by       .
     7            7          7                        7

                  5 7
          =                             Product property of radicals
                  49

                  5 7
          =                             Simplify.
                  7

     2                2          3b                   3b
b.            =             •           Multiply by           .
     3b               3b         3b                   3b
Example 4        Rationalize the denominator

            6b
      =                       Product property of radicals
            9b2

                 6b
      =                       Product property of radicals
            9 • b2

        6b
      =                       Simplify.
        3b
Example 5     Add and subtract radicals

                                                      Commutative
a. 4 10 + 13 – 9 10 = 4 10 – 9 10 +                13 property

                                                      Distributive
                         = (4 – 9) 10 +       13      property

                         = – 5 10 +      13           Simplify.


                                       Factor using perfect square
b. 5 3 +    48 = 5 3 +    16 • 3       factor.

              = 5 3 +     16 •     3   Product property of radicals

              = 5 3 +4 3               Simplify.
Example 5   Add and subtract radicals

            = (5 + 4) 3         Distributive property

            = 9 3               Simplify.
Example 6         Multiply radical expressions


a.    5 (4 –   20 ) = 4       5 –      5 •    20       Distributive property

                        = 4   5 –      100             Product property of
                                                       radicals

                        = 4   5 – 10                   Simplify.


b.   ( 7 +     2 )( 7 – 3       2 )


=    7( 7 – 3     2) +        2( 7 – 3       2 )                 Distributive
                                                                 property

       2
= ( 7 ) +      7 (– 3    2) +    2 •     7 +       2 (– 3   2)   Distributive
                                                                 property
Example 6        Multiply radical expressions


  = 7 – 3   7 • 2 +        7 • 2 – 3 ( 2 )2     Product property
                                                of radicals

  = 7 – 3   14 +      14   – 6                  Simplify.

  = 1 – 2   14                                  Simplify.
8.4 Warm-Up (Day 1)
1.   48
2.   4x   2


3.
     50 × 18
4.
     3b × 18b
       3


5.   7
     81
8.4 Warm-Up (Day 2)
1.   75xy × 2x   3


     4
2.
      3
3.    1
      2x
4.
     2 6 - 5 54
5.
       (
      6 7 3+6        )

8.4

  • 2.
    Vocabulary  Radical Expression– expression that contains a radical, such as a square root, cube root, or other root.  Simplest form of a radical expression:  No perfect square factors are in the radicand.  No fractions are in the radicand.  No radicands appear in the denominator of a fraction.
  • 3.
    Product Property ofRadicals  The square root of a product equals the product of the square roots of the factors. ab = a × b where a ³ 0 and b ³ 0 4x = 4 × x = 2 x
  • 4.
    Example 1 Use the product property of radicals = a. 32 16 • 2 Factor using perfect square factor. = 16 • 2 Product property of radicals = 4 2 Simplify. 9 • x2 • x = b. 9x3 Factor using perfect square factors. 9 • x2 • = x Product property of radicals = 3x x Simplify.
  • 5.
    Example 2 Multiply radicals 2• 8 2•8 = a. Product property of radicals = 16 Multiply. = 4 Simplify. 3x • 4 x 4 3x • x = b. Product property of radicals = 4 3x2 Multiply. 4• 3• = x2 Product property of radicals = 4x 3 Simplify.
  • 6.
    Example 2 Multiply radicals 7xy2 • 3 x 3 7xy2 • x = c. Product property of radicals = 3 7x2y2 Multiply. 3• 7• x2 • y2 Product property of radicals = = 3xy 7 Simplify.
  • 7.
    Quotient Property ofRadicals  The square root of a quotient equals the quotient of the square roots of the numerator and denominator. a a = where a ³ 0 and b > 0 b b 16 16 4 = = 25 25 5
  • 8.
    Example 3 Use the quotient property of radicals a. 13 13 Quotient property of radicals = 100 100 13 = Simplify. 10 b. 7 7 2 = Quotient property of radicals x x2 7 Simplify. = x
  • 9.
    Rationalizing the denominator The process of eliminating a radical from an expression’s denominator is called rationalizing the denominator.
  • 10.
    Example 4 Rationalize the denominator 5 5 7 7 a. = • Multiply by . 7 7 7 7 5 7 = Product property of radicals 49 5 7 = Simplify. 7 2 2 3b 3b b. = • Multiply by . 3b 3b 3b 3b
  • 11.
    Example 4 Rationalize the denominator 6b = Product property of radicals 9b2 6b = Product property of radicals 9 • b2 6b = Simplify. 3b
  • 12.
    Example 5 Add and subtract radicals Commutative a. 4 10 + 13 – 9 10 = 4 10 – 9 10 + 13 property Distributive = (4 – 9) 10 + 13 property = – 5 10 + 13 Simplify. Factor using perfect square b. 5 3 + 48 = 5 3 + 16 • 3 factor. = 5 3 + 16 • 3 Product property of radicals = 5 3 +4 3 Simplify.
  • 13.
    Example 5 Add and subtract radicals = (5 + 4) 3 Distributive property = 9 3 Simplify.
  • 14.
    Example 6 Multiply radical expressions a. 5 (4 – 20 ) = 4 5 – 5 • 20 Distributive property = 4 5 – 100 Product property of radicals = 4 5 – 10 Simplify. b. ( 7 + 2 )( 7 – 3 2 ) = 7( 7 – 3 2) + 2( 7 – 3 2 ) Distributive property 2 = ( 7 ) + 7 (– 3 2) + 2 • 7 + 2 (– 3 2) Distributive property
  • 15.
    Example 6 Multiply radical expressions = 7 – 3 7 • 2 + 7 • 2 – 3 ( 2 )2 Product property of radicals = 7 – 3 14 + 14 – 6 Simplify. = 1 – 2 14 Simplify.
  • 16.
    8.4 Warm-Up (Day1) 1. 48 2. 4x 2 3. 50 × 18 4. 3b × 18b 3 5. 7 81
  • 17.
    8.4 Warm-Up (Day2) 1. 75xy × 2x 3 4 2. 3 3. 1 2x 4. 2 6 - 5 54 5. ( 6 7 3+6 )

Editor's Notes

  • #10 Day 2
  • #17 1. 4 rad(3) 2. 2x 3. 30 4. 2b^2 rad(6) 5. rad(7) / 9
  • #18 1. 5x^2 rad(6y) 2. 4 rad(3) / 3 3. rad(2x) / 2x 4. -13 rad(6) 5. 21 rad(2) + 6 rad (6)