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Pre-Algebra Chapter 1. Algebraic Expressions and Integers. Section 1-1 Variables and Expressions. is a letter or a symbol that replaces a number. Variable. Variable expression. is a mathematical phrase that uses variable, numbers and operation symbols. Numerical expression.
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Pre-Algebra Chapter 1 Algebraic Expressions and Integers
Section 1-1 Variables and Expressions is a letter or a symbol that replaces a number. • Variable • Variableexpression is a mathematical phrase that uses variable, numbers and operation symbols. • Numerical expression is a mathematical phrase that uses numbers and operation symbols.
Examples Identify each expression as a numerical expression or a variable expression. For a variable expression, name the variable. • 7 x 3 • 8 + m • x + y • 27/9 • 5m • k
1-2 The Order of Operations Remember order of operation by the following saying: Please Excuse My Dear Aunt Sally
Examples Simplify the following numerical expressions using the order of operations. a. 8-2(2) b. 12/3-1(2)+1 c. 20-3[(5+2)-1]
1-4 Integers and Absolute Value • Numbers that are the same distance from zero on a number line but in opposite directions are called opposites. • Integers are the set of whole numbers and their opposites. • A number’s distance from zero on a number line is called its absolute value.
1-5 Adding Integers When adding opposites, the sum is zero
Rules for Adding Integers • The sum of two positive integers is positive. The sum of two negative integers is negative. • Same Signs: • Different Signs: To add two integers with signs, find the difference of their absolute values. The sum has the sign of the integer with the greater absolute value.
How to remember rules for Adding integers • S • A • D • S Same Signs Add Different Signs Subtract