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Five-Minute Check (over Lesson 12–2) Main Idea and Vocabulary Example 1: Solve an Equation by Subtracting Example 2: Solve an Equation Using Zero Pairs Key Concept: Subtraction Property of Equality Example 3: Use an Equation to Solve a Problem • Solve addition equations. • inverse operations • Subtraction Property of Equality Solve an Equation By Subtracting Solve x + 4 = 5. Method 1 Use models. Model the equation. Remove 4 counters from each side. Solve an Equation By Subtracting Method 2 Use symbols. x+4= 5 –4=–4 x= 1 Write the equation. Subtract 4 from each side to “undo” the addition of 4 on the left. 5–4=1 Answer: The solution is 1. Check 1+4=5 Solve x + 7 = 13. A. x = – 20 B. x = – 6 C. x = 6 D. x = 20 1. 2. 3. 4. A B C D Solve an Equation Using Zero Pairs Solve x + 11 = 7. Check your solution. Method 1 Use models. Solve an Equation Using Zero Pairs Solve an Equation Using Zero Pairs Method 2 Use symbols. x + 11 = 7 – 11 = – 11 Write the equation. Subtract 11 from each side. x= –4 Answer: The solution is –4. Check x + 11 = 7 ? –4 + 11 = 7 7=7 Write the equation. Replace x with –4. This sentence is true. Solve m + 9 = 3. A. m = –12 B. m = –6 C. m = 6 D. m = 12 0% 0% A B 1. 2. 3. 4. 0% C A B C D 0% D Use an Equation to Solve a Problem PENNSYLVANIA The width of Pennsylvania (from north to south) is 280 miles. This is 120 miles more than the length of the state (from east to west). Write and solve an addition equation to find the length of Pennsylvania. Words length plus 120 miles is 280 miles Variable Let x represent the length of Pennsylvania. Equation x + 120 = 280 Use an Equation to Solve a Problem x + 120 = 280 – 120 = –120 x = 160 Write the equation. Subtract 120 from each side. 280 – 120 = 160 Answer: So, the length of Pennsylvania is 160 miles. INTERNET Steve was on the Internet for 40 minutes last night. This was 15 more minutes than Beth spent on the Internet the same night. Write and solve an addition equation to find the amount of time Beth spent on the Internet last night. A. 15 – t = 40; 20 minutes B. 15 + t = 40; 25 minutes 0% C 0% B D. 40 – t = 15; 55 minutes A 0% 0% D C. 40 + t = 15; 25 minutes 1. 2. 3. 4. A B C D End of the Lesson Five-Minute Check (over Lesson 12–2) Image Bank Math Tools Solving Equations Using Addition and Subtraction (over Lesson 12-2) Simplify 7 + (x + 2). A. 7x + 14 B. 9 + x C. 9 – x D. 14 + x 0% 0% A B 1. 2. 3. 4. 0% C A B C D 0% D (over Lesson 12-2) Simplify (x ● 4) ● 4. A. 4x ● 16 B. 4x ● 4 C. 16x D. 8x 0% 0% A B 1. 2. 3. 4. 0% C A B C D 0% D (over Lesson 12-2) Simplify 9(6x). A. 54x B. 15x C. 6x ● 9 D. 54 + x 0% 0% A B 1. 2. 3. 4. 0% C A B C D 0% D (over Lesson 12-2) Simplify 7x + 2 + x. A. 9x B. 8x + 2 C. 7x + 2 D. 6x + 2 0% 0% A B 1. 2. 3. 4. 0% C A B C D 0% D (over Lesson 12-2) Simplify 4x + 4x. A. 8x B. 16x C. 0 D. 16x2 0% 0% A B 1. 2. 3. 4. 0% C A B C D 0% D (over Lesson 12-2) Simplify x + 3 + 5x. A. 8x B. 8x2 C. 6x + 3 0% 0% A B D. 15x2 1. 2. 3. 4. 0% C A B C D 0% D (over Lesson 12-2) Which of the following is true concerning the expression 5x + 7 + 2x? A. 5x and 7 are like terms. B. The simplified form of the expression is 5x + 9. C. 5x and 2x are like terms. D. The simplified form of the expression is 14x. 0% 0% A B 1. 2. 3. 4. 0% C A B C D 0% D