Equations
equation ­ a sentence stating that 2 expressions are equal
open sentence ­ an equation having at least one variable, the solution is a number that makes the open sentence true
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solving equations ­ when solving equations some properties of equality are used
Properties of Equality
Reflexive ­ every number equals itself
Symmetric ­ If a = b, then b = a
Transitive ­ If a = b and b = c, then a = c
Substitution ­ variable or expressions may be replace with a value they are equal to
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addition, subtraction, multiplication and division properties of equality allow us to solve equations by adding, subtracting, multiplying or dividing BOTH sides of an equation by the same number.
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Solve a One­Step Equation
Examples:
1. a + 4.39 = 76
2. x ­ 5.86 = .002
3. ­3/5 d = 18
4. 18 = 2t
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Solving for a Variable
d = rt (for r)
V = 1/3 πr2h (for h)
S = πrl + πr2 (for l)
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Name That Property
Name the property demonstrated by each.
a. If x = 2 and 2 = 1 + 1, then x = 1 + 1.
b. If x + 7 = 9, then x = 2.
c. 12a = 12a
d. If a ­ 10 = 15, then a = 25.
e. If x = 9, then 9 = x.
f. If 15 = 5x, then 3 = x.
g. If (2 + 3)x = 10, then 5x = 10
h. If x/2 = 10, then x = 20
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Assignment
page 24 16, 19 ­ 26, 35 ­ 40, 42 ­ 52E, 58
page 18 1­10
Quiz Tomorrow:
Chapter1:1­3
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