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Wednesday, April 6, 2011

Pre Algebra (Period 2 & 4)

Powers of Products & Quotients 5-9

(4∙2)3 = (4∙2)∙(4∙2)∙(4∙2)
= 4∙4∙4∙2∙2∙2
= (4∙4∙4)∙(2∙2∙2)
=43∙23

Raising a Product to a Power

(5∙3) 4 = 53∙33

or Algebraically:
(ab)m = ambm

Remember to simplify an expression, you write it with NO like terms or paranthese.

Simplify (4x2)3
Raise each factor to the power 3
= 43∙x23
Use the rule for Raising a Power to a Power
=43∙x6
simplify
= 64x6

WE did several of these in class:
(2p)4 = (2∙2∙2∙2)∙(p∙p∙p∙p)
= 16p4

(xy2)5 = x5y10

(5x3)2 = 25x6

The location of a negative sign affects the value of an expression. Look at the differences between the following

(-5x2 = (-5)2x2 = (-5)(-5)x2 = 25x2

-(5x)2 = - (5)(5)x2 = -25x2


(-2y)4 = 16y4
-(2y)4 = -16y4

Do you see the subtle differences? Make sure you can determine why one is postive and the other is negative

Finding Powers of Quotients

(4/5)3 = (4/5)(4/5)(4/5)

or
4∙4∙4
5∙5∙5
=
43
53
= 64/125

To raise a quotient to a power, raise both the numerator and the denominator to the power

(2/3)4 =

24
34
=
16/81

(1/2)3 =
1/8

(-2/3)4
16/81

Why is it positive?

(2x2/3)3=

8x6/27


∙∙∙

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