Algebraic Expressions Notes 7 th Grade Algebraic Expression

Algebraic Expressions Notes 7 th Grade

Algebraic Expression An Algebraic Expression is a mathematical phrase that can contain: Ø ordinary numbers Ø variables (like x or y) Ø operators (addition, subtraction multiplication and division)

Variables, operators and expressions l. A variable is a letter that stands for a missing number. l An operator is add, subtract, multiply or divide. l An expression puts variables together with operators.

Examples: a+1 a-b 3 x x-a/b ØA number plus one Ø The difference between “a” and “b” Ø The product of three and a number Ø A number “a” divided by a number “b” less than a number “x”

Key Words Addition ü increased ü more than ü combined ü total of ü sum ü added to by

Key Words Subtraction ü less than ü fewer than ü reduced by ü decreased by ü difference

Key Words Multiplication w( t ) ü of (w)(t) ü times ü multiplied by w • t wt

Key words ü ü ü Division per a out of ratio of quotient of ÷

Phrase to Expression l l l nine increased by a number x 9+x fourteen decreased by a number p 14 - p seven less than a number t t-7 the product of 9 and a number n 9 · n or 9 n thirty-two divided by a number y 32 ÷ y or

The use of “than” l Whatever comes after the word “than” ALWAYS goes first! a number less than 5 5 -b a number more than 7 7+n

Practice 1. 2. 3. 4. 5. 6. Fifteen less than twice a number Three times a number, increased by seventeen The product of nine and a number, decreased by six 30 + 7 n 4/a - 5 Jenny earns $30 a day working part time at a supermarket. Write an algebraic expression to represent the amount of money she will earn in “d” days.

Answers 1. 2. 3. 4. 5. 6. 2 a - 15 3 a + 17 9 a - 6 Seven times a number more than 30 Five less than four divided a number 30 d

Vocabulary & Essential Question Complete the Frayer Model for each word. 1. Variable 2. Ratio 3. Proportion 4. Algebraic Expression 5. Equation Essential Question: How is an algebraic equation like a balance?