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Algebraic Expressions Intro to Algebra Numerical Expression A numerical expression represents one value and can contain one or more numbers and operations. 4 + 5 is a numerical expression. It represents the value 9. Example Which numerical expressions represent a value of 21? a) 9 + 24 b) 4 + 7 + 14 c) 9 + 4 + 10 d) 7 x 3 e) 5 + 2 x 2 - 1 f) 160 ÷ 8 What if they are not numbers? 7+x 4y + 3 8–y÷2 Variables A variable is a symbol that can represent different values. We can substitute numbers in for variables to give the expression a value. A Number next to a Variable What does it mean when a number is written next to a variable? 4x it means to multiply. 4x means 4 times x. Examples 1. In the expression x – 4, what is the value when x = 10? 2. In the expression 5y + 2, what is the value when y = -2? 3. In the expression a = -56? 𝑎 7 , what is the value when Evaluating more expressions 1. p + 11 – q (when q = 16, p = 32) 2. 1 ÷ x · y (when y = 4, x = 1) 3. 14 + b · c (when b = 2, c = 3) Algebraic Expression An algebraic expression contains variables, numbers and operations. The value of an algebraic expression can change. Parts of an Algebraic Expression • Terms – A term can be a constant, a variable, or a number with a variable. Terms are separated by either a + or a – sign. • Coefficient – In a single term containing a number and a variable, the number in front of the variable is called the coefficient. Creating Algebraic Expressions Create an algebraic expression to represent the following statements. 1. 5 more than a number. 2. 17 less than a number. Remember… Does order matter in addition and/or subtraction? Subtraction only A word to be careful with… Less than Order is opposite Create an Algebraic Expression 1. Andy had 14 pencils, but then he lost some. 2. Jake had a number of baseball cards, and then he got 24 more. 3. Diane reduced the number of calories she ate by 50.