Transcript Expressions
Expressions Students will be able to identify, write, and evaluate simple expressions. Numerical Expression A numerical expression is a mathematical phrase that includes only numbers and operation symbols. Numerical expressions are what you have been working with. Set up a numerical expression for: – A running back gained 42 yards in the first half and 56 yards in the second half. Variable A variable is a letter or symbol that can stand for one or more numbers. Numerical expressions do not contain variables. Expressions that contain variables are called algebraic expressions. The branch of math that involves variables is called algebra. Algebraic Expression An algebraic expression contains a variable. Here are some examples: – – – – a+3 6–y t + 32 5p Algebraic Expressions There are several ways to write multiplication in an expression. –7 x a can be written as: –7a –7(a) –7 ● a Algebraic Expressions When a plus or minus sign separates the expression into parts, each part is called a term. In the expression v + 3, v is a term and 3 is a term. If the term does not contain a variable it is a constant. 3 would be a constant in the previous example. Algebraic Expression A coefficient is a numerical term that contains a variable and a number. In 7c + 8, 7c is a term and 8 is a term. 8 would be a constant, c is the variable, and 7 is a coefficient. Word Expressions Word expressions are expressions that use words. A word expression can be changed into a numerical or algebraic expression. Three dollars less than five dollars can be changed to 5-3. Two times a distance, d can be 2d Evaluate To evaluate a numerical expression you find its value. If you evaluate 42 + 56, you get a sum of 98. To evaluate an algebraic expression you replace the variable with a number and then find the value. – a + 150, for a = 18 – 18 + 150 = 168 Evaluate Sometimes you will need to predict and test to solve algebraic expressions, because you will not be given the value of the variable every time.