2-5 HW = Pg. 99- 101 #6-50 e, 56-57

2-5 HW Continued

56.) C 57.) B

Quiz 2 #1-12

Wir2.5• LESSON

Reciprocal = the flip of a fraction or whole number so that the product of a number and it’s reciprocal is 1.

- called Inverse Property of Multiplication

- the reciprocal of a is when

- the reciprocal of

Division Rule = to divide (find the quotient) a number a by a nonzero number b, multiply a by the reciprocal of b

-

2-6 Division of Real Numbers

1

a0a

b as long as a 0 or b 0

a

ais

b

1 1 1 -1 3=-1

3 3a b a

b

Another way to look at division of fractions:

• Try to make the denominator a WHOLE #.• Whatever you do to the DENOMINATOR

you MUST do to the NUMERATOR.Examples:

5 5 5 2 5 29 91.) 2.

7)

2 297

9 99

Answers:

5

9

9

2

99

5

9

5

2

95

189

7

2

7

7

7

3

18

5

Sign of a quotient

• Same signs: (-)/(-) = + or (+)/(+)=+– take quotient of absolute values– answer is POSITIVE

• Different signs: (-)/(+) = - or (+)/(-) = -– take quotient of absolute values– answer is NEGATIVE

PracticeFind the quotient.

:

11.) 7 7 2 14

21

2.) 10 (- ) 10 ( 5) 505

3.) -12 3 = -4

16 9 94.) 16 8 72

-2 2 1936 6 216 1

5.) 36 435 5 5 56

3 5 56.) -87 (- ) 87 29 145

5 3 1

Answers

11.) 7

21

2.) 10 (- )5

3.) -12 3

164.)

-2936

5.) 56

36.) -87 (- )

5

Practice 2Simplify the expression

2

11.) 6t (- )

2x

2.) - 312

3y 13.)

4 23

4.) 33x11

45.) 8x ( )

52w

6.) -7 (- )-7

2 2 2 2

Answers:

11.) 6t (- ) = 6t (-2) = -12t

2x 1

2.) - 312 12 3 36

3y 1 3 33.) 2

4 2 4 23 11

4.) 33x 33 11 11 12111 3

4 55.) 8x ( ) 8 ( ) 2 5 10

5 42w

6.) -7 (- ) 2-7

x x

y y

x x x

x x x

w

Practice 3Evaluate the expression

2

3r-71.) when r = 7

11

15x 10 22.) when x = -3 and y =

y 3

3a-4b 1 13.) when a = - and b =

ab 3 4

2

Answers:

3(17)-7 51-7 441.) = 4

11 11 11

15(-3) 10 3 3 3 435 12.) =(15 9+10) (135 10) 145 217

2 2 2 2 2 23

1 13(- )-4( ) -1-1 123 43.) = 2 ( ) 24

1 1 1 1(- )( ) -3 4 12

Summary• The product of a number and ___ is 1.• Ans: reciprocal• Is dividing by a number the same as multiplying by the

opposite of the number? EXPLAIN your reasoning. • Ans: No, dividing is the same as multiplying by the

reciprocal• Is the reciprocal of a negative number sometimes, always or

never positive? • Ans: never• Describe the error shown below:

2 36 6 =9

3 2

Check Yourself

Pg. 106-108 #8-46e,59-60