1. 1-6 Writing Expressions Objective (things to learn): With this section you will need to learn how to evaluate variable expressions. Terms to Know 1. Variable-is a symbol or letter used to represent a number. 2. Algebraic expression-is a collections of numbers, variables, operations, and grouping symbols.

2. 1-6 Writing Expressions The following is a list of Algebraic expressions and there meanings: Algebraic expressions Meanings 15y 15 times y 7 times a, divided by b 3 times m, plus 6

3. 1-6 Writing Expressions Next, let’s look at how to evaluate some algebraic expressions. Example 1 Evaluate 3x + 7y when x = 4 and y = 2. Solution: to evaluate this expression, simply substitute 4 for x and 2 for y. 42 First, write the expression. Then substitute 4 for x and 2 for y. Simplify 3(4) and 7(2). Then add. SOLUTION

4. 1-6 Writing Expressions Let’s look at how to evaluate another algebraic expressions. Example 2 Evaluate x + (5x - 8) when x = 3. Solution: to evaluate this expression, simply substitute 3 for each x. Substitute 3 for x twice. SOLUTION Simplify 5·3. Simplify 15 - 8.

5. 1-6 Writing Expressions Remember, to evaluate an expression use the following flow chart and show your work!!!! Write the algebraic expression. Substitute values for variables. Simplify the numerical expression.

6. 1-6 Writing Expressions Example 3 Representing real life situations. Recall: the Area of a rectangle is equal to the length times the width. A = lw Suppose the length of a rectangle is 12in. and the width of the rectangle is 5in.. What is the Area of the rectangle? SolutionUse the formula A = lw A = (12in.)(5in.) = 60 sq. in.