Do Now 10/2/09
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Take out HW from last night.
 Text p.81, #10-21 all, #33-35 all
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Copy HW in your planner.
 Text p.74, #12-48 evens
 Quiz sections 2.1-2.3 Thursday
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In your journal, find the perimeter of
the figure. (Hint: The answer will be
a variable expression).
3x
x+2
x+2
5x
Simplifying Expressions in
Geometry
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What is the perimeter of the trapezoid?
Perimeter is the
distance around a figure.
3x
Add together each of the sides.
1x + 2
1x + 2
5x
1x + 2 + 3x + 1x + 2 + 5x
(reorder terms)
1x + 3x + 1x + 5x + 2 + 2
(combine like terms)
10x + 4
Homework
Text p.81, #10-21 all, #33-35 all
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10) terms: 10x, 7, 3x; like terms: 10x & 3x; coefficients: 10 & 3;
constant terms: 7; simplified: 13x +7
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11) terms: 4y, 23, -1y, -6; like terms: 4y & -1y; 23 & -6; coefficients: 4 & -1;
constant terms: 23 & -6; simplified: 3y + 17
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12) terms: -19, -11a, 1a, 16; like terms: -11a & 1a, -19 & 16; coefficients: -11 & 1;
constant terms: -19 & 16; simplified: -10a – 3
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13) terms: 2b, -8, 4b, -6b; like terms: 2b, 4b, & -6b; coefficients: 2, 4, & -6;
constant terms: -8; simplified: -8
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14) terms: 9, 1n, -1, -7n; like terms: 1n & -7n, 9 & -1; coefficients: 1 & -7;
constant terms: 9 & -1; simplified: -6n +8
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15) terms: 8p, -5p, 5, -1p, -2; like terms: 8p, -5p & -1p; 5 & -2;
coefficients: 8, -5, & -1; constant terms: 5 & -2; simplified: 2p + 3
Homework
Text p.81, #10-21 all, #33-35 all
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16) 6x
17) 7a
18) -8b
19) 6x
20) 7c²
21) 21y
33) x + x + 5 + 2x + 1; 4x + 6
34) a + 2a + (10 – 3a); 10
35) 7y – 5 + 2y + 7y – 5 + 2y; 18y – 10
Objective
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SWBAT apply the distributive property to
solve problems
Evaluate.
5(11 + 2)
65
This means to multiply
5(11) + 5(2)
65
Section 2.2, “The Distributive Property”
DISTRIBUTIVE PROPERTY-
a(b + c) = ab + ac
a(b - c) = ab - ac
Both of these expressions are
EQUIVALENT EXPRESSIONSmeaning they have the same value.
The Distributive Property
Order doesn’t matter…
DISTRIBUTIVE PROPERTY-
(b + c)a = ba + ca
(b - c)a = ba - ca
Both of these expressions are
EQUIVALENT EXPRESSIONSmeaning they have the same value.
Distributive Property
Multiply across Parentheses
3(2 + 4) = 3(2) + 3(4)
3(6) = 6 + 12
18
=
18
Think of it as looking to DISTRIBUTE something
Evaluate
A.
3(x + 7)
B.
-2(a + b)
C.
(8 – 7)(-9)
D.
10(x + 2y - z)
A). 3(x) + 3(7)
3x + 21
B). -2(a) + -2(b)
-2a + (-2b) or
-2a – 2b
C). (8)(-9) + (-7)(-9)
-72 + 63 = -9
D). 10(x) + 10(2y) - 10(z)
10x + 20y - 10z
Find the Area of the Figures
8 – 12w
9
8 – 3y
12
Area = length x width
Area = (½)bh
Area = (9)(8 – 12w)
Area = (½)(12)(8 – 3y)
Area = 72 – 108w units²
Area = 6(8 – 3y)
Area = 48 – 18y units²
Challenge
3x – (x + 7)
3x + (-1)(x + 7)
3x + (-1x) + (-7)
2x + (-7)
Guided Practice
Text p. 81, #22-30 evens
Homework
-Text p.74, #12-48 evens
Distributive Property
Using Algebra Tiles
Write an expression for the area model.
=x
=1
Use the distributive property
to simplify
2 (x+2)
= 2x+4
=