Simplifying Variable Expressions _Negative Units - Day 2_

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```					Simplifying Variable Expressions
(Negative Units - Day 2)

We are learning to…simplify variable
expressions by combining like terms.
Negative Units
o   As you are working today you may
notice negative units.
o   These units may be shown in one of
two ways.
n   Subtracting positive units.
n   This is because adding a negative is the
same as subtracting a positive.
n   So today pay attention to both the sign and
the operation involved in the expression.
Negative Units
o   When representing Negative Units with Algebra
Tiles you will use the red side of the tile.

xy
xy                         xy
xy

This represents…           This represents…
Positive xy (+xy)          Negative xy (-xy)
o   When drawing your representations today let:
n   Colored in tiles represent positive units.
n   Open tiles represent negative units.
• Draw 2 different
representations of 0 with
Negative Units                  Algebra Tiles.
• Write the expressions that
represent the tiles.

o   Remember…when a positive unit and a negative unit are put
together we create a…

ZERO PAIR
For example the expression below would represent zero:

x2
x2        +         x2
x2

This expression could be written two different ways:

x2 + (-x2) = 0         OR         x2 – x2 = 0
Simplify the expression below:

-2x + 3y – 3x + (-x2) – y + 4x2
Organize the Algebra Tiles so that similar units are next to
Represent the Make Zero Pairs: Algebra Tiles:
expression with
one another:
x
x
x x                                             x2
x2      x2
x2
x x
yy         x
yy         y    x       x
x   x2
x2
y                      yy

x2
x2      x2
x2

Write the simplified version of the expression:

2y – 5x + 3x2
Simplify the expression below:

xy + 4 – 2y2 – 2xy + (-4) – 2y2
Organize the Algebra Tiles so that similar units are next to
Represent the Make Zero Pairs: Algebra Tiles:
expression with
one another:

1
1         y2            xy
xy       1
1       y2
y2
y2

xy        1
1
xy                                         1
1
1
1
y2               1
1             y2
y2
y2        xy
xy
1
1                                1
1

Write the simplified version of the expression:

-xy – 4y2
Practice…
• Now try some practice with your team.
• Directions:
– Use your Algebra Tiles to create a
representation of the expression.
– Draw your representation with Algebra Tiles.
– Organize your tiles so that you combine like
terms in the expression.
– Create Zero Pairs.