Solving Equations by Multiplying or Dividing

Transcription

1 Practice A Solving Equations by Multiplying or Dividing Solve and check = y = z = a 3 = 2 5. b 5 = 6 6. c 9 = n = k = p = m 4 = v 2 = s 13 = t = w = r 15 = a 3 5 = = n = T.J. gave 16 books to the library book sale. This was 1 3 of his books. Write and solve an equation to determine how many books b T.J. had. 20. Sue gathers eggs on her family s farm. She gathers 108 eggs. One egg carton holds 12 eggs. Write and solve an equation to find the number of egg cartons c Sue needs to store the eggs.

2 Practice B Solving Equations by Multiplying or Dividing Solve and check. 1. 4w = y = b = = 9 5. v 6 = n 21 = a = = 3q 9. 23b = k 21 = w 17 = 17 r = = 24b 14. u 25 = m = = t = = 2n Ale scored 13 points in the basketball game. This was 1 of the 5 total points the team scored. Write and solve an equation to determine the total points t the team scored. 20. Jar candles at the Candle Co. cost $4. Nikki spent $92 buying jar candles for party favors. Write and solve an equation to determine how many jar candles c Nikki bought at the Candle Co.

3 Practice C Solving Equations by Multiplying or Dividing Solve and check. 1. 9r = w = p = = 3 5. a 9 = b 7 = k = = 30s 9. 19y = h 32 = d 46 = = z 2 = = y + 3 = k 7 = = 3n w 6 = On a trip from Indianapolis, Indiana, to Houston, Teas, Mr. Sanchez averaged a speed of 63 mi/h. The total distance of the trip was 1071 mi. Write and solve an equation to determine how many hours h it took Mr. Sanchez to drive from Indianapolis to Houston. 20. Ryan charges $5 plus $3 per hour to mow a lawn. He mowed his neighbor s lawn and was paid $ Write and solve an equation to determine how many hours h it took Ryan to mow his neighbor s lawn.

4 Review for Mastery Solving Equations by Multiplying or Dividing To solve a multiplication equation, use division. Solve 3 = 24. Solve 4 = = = 24 3 To solve a division equation, use multiplication. 4 = = 20 4 = 8 = 80 When an equation has two operations, undo addition or subtraction first. Then undo multiplication or division. Solve = = Undo the addition. 2 = = 24 Undo the multiplication. 2 = 12 Tell what number you would multiply or divide by to solve the equation. 1. 5a = = = 12f Solve = = 42 a 3 = = k 5 a 3 = 9 25 = k 5 = a = = k = b = t 9 = 36 2 = b 4 = 5t = b = t = =

5 Challenge Which Square is Magic? A magic square has the same sum for every row, column, and diagonal. In the magic square below, the solution of each equation is a number of the magic square. But, one of the equations has a solution that does not fit in this magic square. Solve each equation. Find the magic sum. Circle the equation that does not fit in this magic square. Write a new equation with a solution that completes the magic square. The magic sum is = = = = = = = = = 1

6 Name Date Teacher Problem Solving Solving Equations by Multiplying or Dividing Write the correct answer. 1. Brett is preparing to participate in a 250-kilometer bike race. He rides a course near his house that is 2 km long. Write an equation to determine how many laps he must ride to equal the distance of the race. 2. The average life span of a duck is 10 years, which is one year longer than three times the average life span of a guinea pig. Write and solve an equation to determine the lifespan of a guinea pig. 3. The speed of a house mouse is one-fourth that of a giraffe. If a house mouse can travel at 8 mi/h, what is the speed of a giraffe? Write an equation and solve. Choose the letter for the best answer. 5. Farmland is often measured in acres. A farm that is 1920 acres covers 3 square miles. Find the number of acres a in one square mile. A 9 acres C 640 acres B 213 acres D 4860 acres 7. The depth of water is often measured in fathoms. A fathom is si feet. If the maimum depth of the Gulf of Meico is 2395 fathoms, what is the maimum depth in feet? A 14,370 ft C 29,250 ft B 98,867 ft D 175,464 ft 4. In 2005, the movie with the highest bo office sales was Titanic, which made about 3 times the bo office sales of Charlie and the Chocolate Factory. If Titanic made about $600 million, about how much did Charlie and the Chocolate Factory make? Write an equation and solve. 6. When Maria doubles a recipe, she uses 8 cups of flour. How many cups of flour are in the original recipe? F 2 cups H 8 cups G 4 cups J 16 cups 8. Four times as many pet birds have lived in the White House as pet goats. Siteen pet birds have lived in the White House. How many pet goats have there been? F 4 H 12 G 20 J 64

7 Reading Strategies Understanding Symbols Reading the words that stand for the symbols in a multiplication or division equation helps you understand what the symbols mean. Write 6n = 72 Read Si times n equals seventy-two. 72 n = 6 Seventy-two divided by n equals si. 1. Use words to write this equation: 35 n = Use words to write this equation: 9n = Use symbols to write this equation: n divided by 8 equals Use symbols to write this equation: seven times n equals 56. To solve a multiplication or a division equation, apply the opposite, or inverse, operation. Multiplication is the inverse operation of division. This is a multiplication problem, so divide to solve. 3 = 51 Divide both sides of equation by = 51 3 On one side you have 3 3 = 1 or On the other side you have 51 3 = 17 The solution to this equation is = 17 Write multiplication or division to tell which operation you would use to get the variable on one side of the equation r = s 3 = t = q 8 = 64.

8 Puzzles, Twisters & Teasers Bird-a-cology? What is the technical term for the study of birds? Solve the equations below. Match the letter above the equations with the answers in the decoder to solve the mystery. 1. O 2. I 3. T 5 = 25 16y = 32 2y = R 5. Y 6. G 72 = 12 7 = 21 9c = N 8. H 9. O 7d = 70 6h = 42 15y = L 11. O 56 = 7 99 s =

9 Answers LESSON 1-9 Practice A 1. = 4 2. y = 9 3. z = 4 4. a = 6 5. b = c = n = 7 8. k = 8 9. p = m = v = s = t = w = r = a = = n = b = 16; b = c = 108; c = 9 Practice B 1. w = y = 7 3. b = = v = n = a = q = b = k = w = r = b = u = m = = t = n = t = 13; t = c = 92; c = 23 Practice C 1. r = 8 2. w = p = 5 4. = 54 CODE 5. a = b = k = s = 9 9. y = h = d = = z = = y = k = n = w = h = 1071; h = h = 11; h = 2 Review for Mastery 1. Divide by Multiply by Divide by Answers are given from left to right. 4. 6; 6; 5. 3; 3; ; 5; 7. 3; 3; 125 2; 8 2 ; 8. 5; 5; 9. +9; +9; 4; 1; 4; 5; 45 5 ; 4 9 Challenge Replacement for the equation in the center bo will vary; but, its solution should be 5. Possible replacement: =

10 Problem Solving 1. 2l = y + 1 = 10; y = 3 3. g 4 = 8; g = 32; 32 mi/h 4. 3s = 600; s = 200; about $200 million 5. C 6. G 7. A 8. F Reading Strategies 1. Thirty-five divided by n equals seven. 2. nine times n equals sity-three. 3. n 8 = n = multiplication 6. multiplication 7. division 8. division Puzzles, Twisters & Teasers 1. = 5 2. y = 2 3. y = = 6 5. = 3 6. c = 9 7. d = h = 7 9. y = = s = 11 O R N I T H O L O G Y