Section 1.1 “Expressions and Variables” Numerical expression consists of numbers and operations 9 + 8 4 - 9 5 ÷ 2 6(10)

Variable a letter used to represent one or more numbers. a y e t k s m

Variable expression consists of numbers, variables, and operations. y – 7 3t + 2y 2k - 7 3m

To EVALUATE A VARIABLE EXPRESSION- substitute a number for each variable, perform the operations and simplify, if necessary. 13· n Substitute 3 for n. 13· 3 Multiply. 39

Evaluate the expression when n = 3. 9 n 9 3 = Substitute 3 for n. = 3 Divide. b. n – 1 = 3 – 1 Substitute 3 for n. = 2 Subtract. Evaluate the expression when y = 2. c. 6 y = 6 2 Substitute 2 for y. = 12 Multiply. d. y + 4 = 2 + 4 Substitute 2 for y.. = 6 Add.

Verbal model describes a problem using words as labels and using math symbols to relate the words ‘sum’ ‘minus’ ‘divided’ ‘times’

Common Words and Phrases that Indicate Operations Verbal Phrase Expression Addition Sum, plus, total, more than, increased by 5 + n k + 12 Subtraction Difference, less than, minus, decreased by 12 – p x – 12 Multiplication Product, times, of, multiplied by 3 x 5 3(d) (n)(w) p ∙ k Division Quotient, divided by, divided into k/7 14 ÷ r

Translate verbal phrases into expressions 7 less than a number n 3y b. 3 times a number y c. the difference of a number x and the square of a number m x – m2 d. the sum of 12.5 and the number c 12.5 + c e. the sum of 5 and the product of 6 and the number f 5 + 6f

Guided Practice Text p. 7, #1-10 all Homework Text p. 7-8, #12-36