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Example 5-1b Objective Solve equations using mental math

Example 5-1b Vocabulary Equation A sentence in math that contains an equal sign

Example 5-1b Vocabulary Solution A number that makes the equation true

Example 5-1b Vocabulary Solving an equation The process of finding a solution

Example 5-1b Vocabulary Defining the variable To choose a variable to represent one of the unknowns

Example 5-1b Math Symbols = is equal to ≠is not equal to

Lesson 5 Contents Example 1Solve an Equation Mentally Example 2Graph the Solution of an Equation Example 3Write an Equation to Solve a Problem Example 4Find a Solution of an Equation

Example 5-1a Solve mentally 1/4 THINK What number divided by 2 equals 3? Replace x with 6 6 Write equation Just because it says “mentally” there is still work to do You know that 2  3 = 6, so try 6 as your solution

Example 5-1b 1/4 Solve mentally 6 Divide 6 by 2 3 Bring down = 3 3 = 3 This is a true statement so 3 is the solution Answer: The solution is 3

Example 5-1b Solve mentally. Answer: 17 1/4

Example 5-2a Graph the solution of the equation 2/4 Write equation Remember: You solved this equation in example 2 and the solution was 6 Draw a number line that includes the solution

Example 5-2a Graph the solution of the equation 2/4 Answer: Plot 6 on the number line

Example 5-2b Answer: Graph the solution of the equation 2/4

Example 5-3a ENTERTAINMENT An adult paid $18.50 for herself and two students to see a movie. If the two student tickets cost $11 together, what is the cost of the adult ticket? Words Variable The cost of one adult ticket plus two student tickets is $ Let a represent the cost of an adult movie ticket. 3/4 Two student tickets cost $11 Total cost is $18.50 Write Equation a + 11 = 18.50

Example 5-3a ENTERTAINMENT An adult paid $18.50 for herself and two students to see a movie. If the two student tickets cost $11 together, what is the cost of the adult ticket? Solve equation mentally 3/4 a + 11 = THINK What number added to 11 = Replace a with = You know that is 7.50, so try 7.50 as your solution

Example 5-3a ENTERTAINMENT An adult paid $18.50 for herself and two students to see a movie. If the two student tickets cost $11 together, what is the cost of the adult ticket? Add / = = Answer: The cost of an adult movie ticket is $7.50. Bring down = This is a true statement so 7.50 is the solution

Example 5-3c ICE CREAM Julie spends $9.50 at the ice cream parlor. She buys a hot fudge sundae for herself and ice cream cones for each of the three friends who are with her. Find the cost of Julie’s sundae if the three ice cream cones together cost $6.30. Answer: $3.20 3/4

Example 5-4c 4/4 MULTIPLE- CHOICE TEST ITEM What value of x is a solution of A 5 B 6 C 7 D 8 Write equation 12 - x = 5 THINK What number subtracted from 12 equals 5 You know that is 7, so try 7 as your solution Replace x with = 5

Example 5-4c 4/4 MULTIPLE- CHOICE TEST ITEM What value of x is a solution of A 5 B 6 C 7 D 8 Subtract 7 from = 5 Bring down = 5 This is a true statement so 7 is the solution Choose the correct multiple choice letter 55 = 5 Answer: C

Example 5-4c What value of x is a solution of MULTIPLE- CHOICE TEST ITEM A 34 B 35 C 36 D 9 Answer: B * 4/4

End of Lesson 5 Assignment Lesson 1:5Algebra: Equations All