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Variables and Expressions. Write the numerical expression for each verbal phrase: The product of eight and seven 8 x 7 The difference of nine and three 9-3 Sixty divided by the sum of two and ten 60 (2+10). Translate Phrases into Expressions.
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Write the numerical expression for each verbal phrase: • The product of eight and seven • 8 x 7 • The difference of nine and three • 9-3 • Sixty divided by the sum of two and ten • 60 (2+10) Translate Phrases into Expressions
A taxicab company charges a fare of $4 for the first mile and $2 for each additional mile. Write and then evaluate an expression to find the fare for a 10-mile trip. • Words: $4 for the first mile AND $2 for each additional mile • Expression: 4+ 2 x 9 Use an expression to solve a problem
A variable is a placeholder for any value • Babysitter earns $5 per hour. If h represents any number of hours, what expression would represent the amount of money earned? • An expression does not contain variables • 1+2, 3+8, 6+9, 7-9, 5-8, etc. • An algebraic expression DOES contain variables • 1 + X, 5 - y, 6 x Z, etc. Variable
2+9 • 3-X • 5•Z • 3/4 Expression or Algebraic Expression
To evaluate algebraic expressions, replace the variable or variables with known values and then use the order of operations. Evaluating Algebraic Expressions
Evaluate X + Y – 9 if X = 15 and Y = 26 X + Y – 9 = 15 + 26 – 9 = 41 – 9 = 32 Evaluate Expressions
The substitution property of equality is demonstrated when you replace a variable with a number • In other words: If two quantities are equal, then one quantity can be replaced with the other. • Symbols: For all numbers a and b, if a = b, then a may be replaced by b Substitution Property of Equality
Evaluate for each expression if k = 2, m = 7, and n = 4 • 6m – 3k • n + (k + 5m) Evaluate Expressions
The first step in translating verbal phrases into algebraic expressions is to choose a variable and a quantity for the variable to represent. • This is called defining a variable Translating Verbal Phrases
Translate each phrase into an algebraic expression • Twelve points more than the Vikings scored • Four times a number decreased by 6 Translate Verbal Phrases into Expressions
The Johnsontown Soccer League ranks each team in their league using points. A team gets three points for a win and one point for a tie. • Write an expression that can be used to find the total number of points a team receives • Suppose in one season, the North Rockets had 17 wins and 4 ties. How many points did they receive? Use an Expression to Solve a Problem