Transcript Section3.3 Subtracting Rational Numbers Revise

Page 114 - 120
 When we subtract rational numbers we are finding
the difference between those two number on a number
line.
 For example 4  6  we need to look at how far we go
from -6 to get to 4.
 Because we move to the right on the number line the
distance is positive!
 We can use this strategy:
 We can Add the opposite of the decimal!
-2.3 – (-3.9) =
-2.3 – (-3.9) =
= -2.3 + (+3.9)
= -2.3 + 3.9
= 1.6
1
2
11
3
Similar steps to adding fractions.
Find the lowest common denominator.
Change both fractions to equivalent fractions.
1 X3
2 X3
11 X 2
3 X2
3
6
1
3
6
22
6
Add the numerators.
3  22
6
19
6
Strategy – change the Mixed Number to an IMPROPER
fraction and follow from there.
5  1
   3 
4  5
Page 119-121
#4, 5 all, 7bdf,
9f, 10, 11, 13cd, 15abc
The following slides are not a part of the
current notes for Section 3.3
 Strategy ONE- is to place the number being subtracted on
a number line and follow from there

5  1
  3 
4  5
 Strategy TWO – is to change the Mixed Number to an
IMPROPER fraction and follow from there.

5  1
  3 
4  5
 It is important to remember that when we are
subtracting rational numbers to use equivalent
fractions. These are numbers that have the same
number of pieces.
 Think ½ and 1/8 - in order to make them equivalent
they both must be out of 8ths
is
1/2 is the same as 4/8 so:
And
4 1 3
 
8 8 8
 Math Makes Sense – SEE IT ( link page 115)